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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Comput. Sci.</journal-id>
<journal-title>Frontiers in Computer Science</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Comput. Sci.</abbrev-journal-title>
<issn pub-type="epub">2624-9898</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/fcomp.2023.1136057</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Computer Science</subject>
<subj-group>
<subject>Original Research</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>The trace consistency measurement between WFD-net systems</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name><surname>Zhao</surname> <given-names>Fang</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/2157827/overview"/>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name><surname>Xiang</surname> <given-names>Dongming</given-names></name>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
<xref ref-type="corresp" rid="c001"><sup>&#x0002A;</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/2224241/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Liu</surname> <given-names>Guanjun</given-names></name>
<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
<xref ref-type="aff" rid="aff4"><sup>4</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/2207150/overview"/>
</contrib>
</contrib-group>
<aff id="aff1"><sup>1</sup><institution>School of Microelectronics and Data Science, Anhui University of Technology</institution>, <addr-line>Maanshan</addr-line>, <country>China</country></aff>
<aff id="aff2"><sup>2</sup><institution>School of Computer Science and Technology, Zhejiang Sci-Tech University</institution>, <addr-line>Hangzhou</addr-line>, <country>China</country></aff>
<aff id="aff3"><sup>3</sup><institution>Key Laboratory of the Ministry of Education for Embedded System and Service Computing, Department of Computer Science and Technology, Tongji University</institution>, <addr-line>Shanghai</addr-line>, <country>China</country></aff>
<aff id="aff4"><sup>4</sup><institution>Shanghai Electronic Transactions and Information Service Collaborative Innovation Center, Tongji University</institution>, <addr-line>Shanghai</addr-line>, <country>China</country></aff>
<author-notes>
<fn fn-type="edited-by"><p>Edited by: Gaiyun Liu, Xidian University, China</p></fn>
<fn fn-type="edited-by"><p>Reviewed by: Xiaoliang Chen, Xihua University, China; Li Yin, Macau University of Science and Technology, Macao SAR, China</p></fn>
<corresp id="c001">&#x0002A;Correspondence: Dongming Xiang <email>flysky_xdm&#x00040;163.com</email></corresp>
<fn fn-type="other" id="fn001"><p>This article was submitted to Theoretical Computer Science, a section of the journal Frontiers in Computer Science</p></fn></author-notes>
<pub-date pub-type="epub">
<day>13</day>
<month>03</month>
<year>2023</year>
</pub-date>
<pub-date pub-type="collection">
<year>2023</year>
</pub-date>
<volume>5</volume>
<elocation-id>1136057</elocation-id>
<history>
<date date-type="received">
<day>02</day>
<month>01</month>
<year>2023</year>
</date>
<date date-type="accepted">
<day>20</day>
<month>02</month>
<year>2023</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#x000A9; 2023 Zhao, Xiang and Liu.</copyright-statement>
<copyright-year>2023</copyright-year>
<copyright-holder>Zhao, Xiang and Liu</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/"><p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p></license> </permissions>
<abstract>
<sec>
<title>Introduction</title>
<p>How to measure the trace consistency between process models in workflow net systems have become a crucial part of process mapping, process integration, and difference testing. Workflow net with data (WFD-net) is an effective language to describe a complete model of a workflow net system. Checking their trace consistency is a significant challenge in service-based software engineering. However, most of the existing research on trace consistency measurement has not taken the data into consideration. Therefore, they cannot accurately calculate the trace consistency degree of two WFD-net systems, especially when data operations and guard functions are complex.</p></sec>
<sec>
<title>Methods</title>
<p>We explore all traces in two WFD-net systems based on guard analysis and data dependencies.</p></sec>
<sec>
<title>Results</title>
<p>We point out that the trace consistency degree is uncertain when the values of guard functions are considered.</p></sec>
<sec>
<title>Discussion</title>
<p>We conduct experiments to evaluate our method and show its effectiveness.</p></sec></abstract>
<kwd-group>
<kwd>trace consistency</kwd>
<kwd>WFD-net system</kwd>
<kwd>data operation</kwd>
<kwd>guard analysis</kwd>
<kwd>data dependency</kwd>
</kwd-group>
<counts>
<fig-count count="10"/>
<table-count count="3"/>
<equation-count count="0"/>
<ref-count count="42"/>
<page-count count="13"/>
<word-count count="7887"/>
</counts>
</article-meta>
</front>
<body>
<sec id="s1">
<title>1. Introduction</title>
<p>Nowadays, business process models with data are very important in the development of business process systems (Song et al., <xref ref-type="bibr" rid="B22">2016</xref>). They are very effective in reflecting the relations of activities. Here, we mainly focus on studying workflow net systems, which can be used to automate, optimize, and manage these business process models. They have become a major way to construct business processes in software systems (IEEE, <xref ref-type="bibr" rid="B6">1990</xref>; Song et al., <xref ref-type="bibr" rid="B21">2018</xref>). Software designers and business analysts may simulate workflows in the same granularity standards but with different extra activities (i.e., activities without correspondences). Meanwhile, service-based workflow net systems become more and more extensive, and the traces (i.e., firing sequences of transitions) of a system may be affected by data. Therefore, we should provide an effective way to measure the trace consistency of these workflow net systems.</p>
<p>Many models can be taken to describe workflow net systems, i.e., UML activity diagram (Fahland, <xref ref-type="bibr" rid="B5">2008</xref>), Business Process Modeling Notation (BPMN) (van der Aalst et al., <xref ref-type="bibr" rid="B28">2010</xref>; Zhu et al., <xref ref-type="bibr" rid="B42">2014</xref>; Assy et al., <xref ref-type="bibr" rid="B1">2015</xref>), Business Process Execution Language (BPEL) (Weidlich et al., <xref ref-type="bibr" rid="B32">2014</xref>), Event-driven Process Chain (EPC) (Dijkman et al., <xref ref-type="bibr" rid="B4">2011</xref>; Li et al., <xref ref-type="bibr" rid="B7">2014</xref>), and Workflow net with data (WFD-net) (Trcka et al., <xref ref-type="bibr" rid="B25">2009</xref>; Sidorova et al., <xref ref-type="bibr" rid="B19">2011</xref>). Unfortunately, the first four modeling languages have not taken the delete operations into consideration. Compared with these modeling methods, WFD-net is a workflow net with data operations and guard functions. Therefore, we use WFD-net as an adequate formalism to model workflow net systems (Trcka et al., <xref ref-type="bibr" rid="B25">2009</xref>; Sidorova et al., <xref ref-type="bibr" rid="B19">2011</xref>) to analyze the trace consistency in this paper.</p>
<p>At present, many methods are used to measure the trace consistency degree, e.g., DTC (Degree of Trace Consistency) (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>) and CDAT (Consistency Degree of Aligned Traces) (Wang et al., <xref ref-type="bibr" rid="B30">2018</xref>). Based on the sets of projected firing sequences, the first method can be used to obtain the trace consistency degree of two models without data. Based on the direct dependence relations and independence relations on transitions, the second method is used to calculate the trace consistency degree of two traces. Moreover, these methods only considered transitions with correspondence relations, while those without correspondence relations are ignored. However, they may affect the traces of transitions with correspondences. Therefore, these methods are ambiguous and cannot reflect the real traces in two models, especially when there are guard functions and data dependencies. They cannot accurately assess the trace consistency degree of systems with data information. Furthermore, calculating the trace consistency degree would require a lot of work, e.g., if there are <italic>k</italic> concurrently-executed transitions in a process, then there are <italic>k</italic>! different traces at most. Therefore, calculating the trace consistency degree would require a lot of work.</p>
<p>To solve these problems, a new behavioral profile relation is defined based on weak behavioral relations, guard functions, control and data dependency. After then, the formalization of correspondence relation and projected firing sequence are provided. Finally, we develop a new method to calculate <italic>trace consistency degree</italic>.</p>
<p>The contributions of this paper are shown in the following:
<list list-type="order">
<list-item><p>We reveal that the trace consistency degree of two WFD-net systems is non-uniqueness when their guard functions are uncertain since these guard functions may affect the real traces.</p></list-item>
<list-item><p>We point out that transitions without correspondence relations but with data dependencies should not be ignored as they may affect the traces of the systems.</p></list-item>
<list-item><p>We minimize the number of traces in WFD-net systems based on guard functions and data dependencies.</p></list-item>
</list></p>
<p>The rest of this paper is arranged as follows. Section 2 introduces some basic concepts used in this paper and provides a motivating example. Section 3 defines control dependency, data dependency and behavioral profile relations, order relation, firing sequence, trace, correspondence relation, projected firing sequence and trace consistency measurement method. Section 4 presents experiments to show that guard functions and data dependencies can affect the traces in WFD-net systems. Section 5 reviews the related work about the existing consistency measurement methods. Section 6 concludes this paper and presents future work.</p></sec>
<sec id="s2">
<title>2. Preliminaries and motivation</title>
<p>In this section, we first introduce some concepts about WF-net, weak order relation, weak behavioral profile, and WFD-net. Some symbols are demonstrated in <xref ref-type="table" rid="T1">Table 1</xref>. The related details can be found in Li and Liu (<xref ref-type="bibr" rid="B8">2009</xref>), Weidlich and van der Werf (<xref ref-type="bibr" rid="B35">2012</xref>), Liu et al. (<xref ref-type="bibr" rid="B13">2017</xref>), Liu et al. (<xref ref-type="bibr" rid="B11">2018</xref>), Xiang et al. (<xref ref-type="bibr" rid="B36">2021</xref>), and Zhao et al. (<xref ref-type="bibr" rid="B40">2022a</xref>). Furthermore, a motivating example is given.</p>
<table-wrap position="float" id="T1">
<label>Table 1</label>
<caption><p>Common symbols used in this paper.</p></caption>
<table frame="box" rules="all">
<thead>
<tr style="background-color:#919498;color:#ffffff">
<th valign="top" align="left"><bold>Symbols</bold></th>
<th valign="top" align="left"><bold>Descriptions</bold></th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">&#x02115;</td>
<td valign="top" align="left">Set of positive integers</td>
</tr> <tr>
<td valign="top" align="left">BP</td>
<td valign="top" align="left">Weak behavioral profile</td>
</tr> <tr>
<td valign="top" align="left">MD</td>
<td valign="top" align="left">Missing data</td>
</tr> <tr>
<td valign="top" align="left">BP</td>
<td valign="top" align="left">Behavioral profile</td>
</tr> <tr>
<td valign="top" align="left">DTC</td>
<td valign="top" align="left">Degree of trace consistency (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>)</td>
</tr> <tr>
<td valign="top" align="left">TCDW</td>
<td valign="top" align="left">Trace consistency degree of WFD-net systems</td>
</tr></tbody>
</table>
</table-wrap>
<sec>
<title>2.1. Preliminaries</title>
<p>A Petri net <italic>N</italic> &#x0003D; (<italic>P, T, F</italic>) as a tool is often used to simulate and analyze the trace (i.e., firing sequences of transitions) of a workflow system (Liu et al., <xref ref-type="bibr" rid="B14">2019</xref>; Zhang et al., <xref ref-type="bibr" rid="B39">2022</xref>), where <italic>P</italic> is a finite non-empty set of places, <italic>T</italic> is a finite non-empty set of transitions, <italic>P</italic> &#x02229; <italic>T</italic> &#x0003D; &#x02205;, and <italic>F</italic> &#x02286; (<italic>P</italic> &#x000D7; <italic>T</italic>) &#x0222A; (<italic>T</italic> &#x000D7; <italic>P</italic>) is a set of arcs. Given a node <italic>x</italic> &#x02208; <italic>P</italic> &#x0222A; <italic>T</italic>, the preset of <italic>x</italic> is <sup>&#x000B7;</sup><italic>x</italic> &#x0003D; {<italic>y</italic>|(<italic>y</italic> &#x02208; <italic>P</italic> &#x0222A; <italic>T</italic>) &#x02229; (<italic>y, x</italic>) &#x02208; <italic>F</italic>}, and the post-set of <italic>x</italic> is <italic>x</italic><sup>&#x000B7;</sup> &#x0003D; {<italic>y</italic>|(<italic>y</italic> &#x02208; <italic>P</italic> &#x0222A; <italic>T</italic>) &#x02229; (<italic>x, y</italic>) &#x02208; <italic>F</italic>}. If <italic>x</italic> is the initial place, it must satisfy <sup>&#x000B7;</sup><italic>x</italic> &#x0003D; &#x02205;; If <italic>x</italic> is the final place, it must satisfy <italic>x</italic><sup>&#x000B7;</sup> &#x0003D; &#x02205;. Given a set of nodes <italic>X</italic> &#x02286; <italic>P</italic> &#x0222A; <italic>T</italic> and <italic>x</italic> &#x02208; <italic>X</italic>, the preset of <italic>X</italic> is denoted by <sup>&#x000B7;</sup><italic>X</italic>, and the post-set of <italic>X</italic> is denoted by <italic>X</italic><sup>&#x000B7;</sup>, where <sup>&#x000B7;</sup><italic>X</italic> &#x0003D; {<italic>Y</italic>|(<italic>Y</italic> &#x02286; <italic>P</italic> &#x0222A; <italic>T</italic>) &#x02227; (<italic>y</italic> &#x02208; <italic>Y</italic>) &#x02227; (<italic>y, x</italic>) &#x02208; <italic>F</italic>} and <italic>X</italic><sup>&#x000B7;</sup> &#x0003D; {<italic>Y</italic>|(<italic>Y</italic> &#x02286; <italic>P</italic> &#x0222A; <italic>T</italic>) &#x02227; (<italic>y</italic> &#x02208; <italic>Y</italic>) &#x02227; (<italic>x, y</italic>) &#x02208; <italic>F</italic>}. In <xref ref-type="fig" rid="F1">Figure 1A</xref>, if <italic>X</italic> &#x0003D; {<italic>t</italic><sub>5</sub>, <italic>t</italic><sub>6</sub>}, we have <inline-formula><mml:math id="M1"><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msup><mml:mi>X</mml:mi><mml:mo>=</mml:mo><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msup><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>5</mml:mn></mml:mrow></mml:msub><mml:mo>&#x0222A;</mml:mo><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msup><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mrow><mml:mo>{</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:msub><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mn>5</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mo>}</mml:mo></mml:mrow></mml:math></inline-formula>, and <inline-formula><mml:math id="M2"><mml:msup><mml:mrow><mml:mi>X</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:msubsup><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>5</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x0222A;</mml:mo><mml:msubsup><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:mrow><mml:mo>{</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mn>5</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:msub><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mo>}</mml:mo></mml:mrow></mml:math></inline-formula>. If we use <italic>k</italic> to denote the preset number, then we have <inline-formula><mml:math id="M3"><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:msup><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>5</mml:mn></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msup><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>5</mml:mn></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mrow><mml:mo>{</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mo>}</mml:mo></mml:mrow></mml:math></inline-formula>, and <italic>k</italic> &#x0003D; 1 (resp. <inline-formula><mml:math id="M4"><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:msup><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msup><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msup><mml:mtext>&#x000A0;</mml:mtext><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math></inline-formula>) &#x0003D; {<italic>p</italic><sub>4</sub>}, and <italic>k</italic> &#x0003D; 3). For the post-set number of <italic>X</italic>, it can be defined analogously.</p>
<fig id="F1" position="float">
<label>Figure 1</label>
<caption><p>Two shipper process models are shown in <bold>(A, B)</bold>. There are no correspondences of <italic>t</italic><sub>9</sub>, <italic>t</italic><sub>10</sub>, and <italic>d</italic><sub><italic>q</italic></sub> in <bold>(B)</bold>.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fcomp-05-1136057-g0001.tif"/>
</fig>
<p>The following parts present the workflow net (WF-net), as a special Petri net satisfying the following conditions (Liu et al., <xref ref-type="bibr" rid="B12">2013</xref>).</p>
<p><bold>Definition 1</bold> [WF-net (Liu, <xref ref-type="bibr" rid="B9">2014</xref>, <xref ref-type="bibr" rid="B10">2022</xref>)]. Let <italic>N</italic> &#x0003D; (<italic>P, T, F</italic>) be a workflow net (WF-net), if the following conditions hold:</p>
<list list-type="order">
<list-item><p>There exists only one place <italic>p</italic><sub><italic>i</italic></sub> &#x02208; <italic>P</italic> as begin and only one place <italic>p</italic><sub><italic>o</italic></sub> &#x02208; <italic>P</italic> as end in <italic>N</italic>; and</p></list-item>
<list-item><p>The short-circuit net <inline-formula><mml:math id="M5"><mml:msup><mml:mrow><mml:mi>N</mml:mi></mml:mrow><mml:mrow><mml:mo>*</mml:mo></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mi>P</mml:mi><mml:mo>,</mml:mo><mml:mi>T</mml:mi><mml:mo>&#x0222A;</mml:mo><mml:mrow><mml:mo>{</mml:mo><mml:mrow><mml:msup><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:mi>&#x02032;</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:msup></mml:mrow><mml:mo>}</mml:mo></mml:mrow><mml:mo>,</mml:mo><mml:mi>F</mml:mi><mml:mo>&#x0222A;</mml:mo><mml:mrow><mml:mo>{</mml:mo><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mi>o</mml:mi></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:msup><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:mi>&#x02032;</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:msup></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>,</mml:mo><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msup><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:mi>&#x02032;</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:msup><mml:mo>,</mml:mo><mml:msub><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mi>i</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow><mml:mo>}</mml:mo></mml:mrow></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math></inline-formula> is strongly connected, where <italic>t</italic>&#x02032; &#x02209; <italic>T</italic>.</p></list-item>
</list>
<p>A WF-net system (<italic>N, M</italic><sub>0</sub>) is a WF-net extended with an initial marking <italic>M</italic><sub>0</sub>. The dynamic behaviors of workflow systems are decided by distributing different markings. <xref ref-type="fig" rid="F1">Figures 1A</xref>, <xref ref-type="fig" rid="F1">B</xref> depict two WF-net systems if the guard functions and data operations are ignored.</p>
<p>In general, we can distinguish three basic weak behavioral relations between transition pairs in a WF-net system, and they are based on the concept of <italic>weak order relation</italic> (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>).</p>
<p><bold>Definition 2</bold> [Weak order relation (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>; Zhao et al., <xref ref-type="bibr" rid="B41">2022b</xref>)]. Given a WF-net system (<italic>N, M</italic><sub>0</sub>) &#x0003D; (<italic>P, T, F, M</italic><sub>0</sub>), the weak order relation &#x0227B;<sub><italic>c</italic></sub> &#x02282; <italic>T</italic> &#x000D7; <italic>T</italic> contains transition pairs <italic>t</italic><sub><italic>x</italic></sub>, <italic>t</italic><sub><italic>y</italic></sub> &#x02208; <italic>T</italic>, there exists a weak firing sequence &#x003C3; &#x0003D; <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub> &#x022EF; <italic>t</italic><sub><italic>n</italic></sub>(<italic>n</italic> &#x02208; &#x02115;) with (<italic>N, M</italic><sub>0</sub>)[&#x003C3; &#x0003E;, <italic>x</italic> &#x02208; {1, 2, &#x022EF;&#x02009;, <italic>n</italic> &#x02212; 1}, and <italic>x</italic> &#x0003C; <italic>y</italic> &#x02264; <italic>n</italic>.</p>
<p>For the example of <xref ref-type="fig" rid="F1">Figure 1A</xref>, we have <italic>t</italic><sub>1</sub> &#x0227B;<sub><italic>c</italic></sub> <italic>t</italic><sub>2</sub> and <italic>t</italic><sub>2</sub> &#x02281;<sub><italic>c</italic></sub> <italic>t</italic><sub>1</sub>. The set of all weak firing subsequences is denoted by <italic>T</italic><sup>&#x0002A;</sup>, and <inline-formula><mml:math id="M6"><mml:msup><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mo>*</mml:mo></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:mrow><mml:mo>{</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow></mml:msub></mml:mrow><mml:mo>}</mml:mo></mml:mrow><mml:mo>&#x0222A;</mml:mo><mml:mrow><mml:mo>{</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow></mml:msub></mml:mrow><mml:mo>}</mml:mo></mml:mrow><mml:mo>&#x0222A;</mml:mo><mml:mo>&#x022EF;</mml:mo><mml:mo>&#x0222A;</mml:mo><mml:mrow><mml:mo>{</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mi>&#x003B5;</mml:mi></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow></mml:msub></mml:mrow><mml:mo>}</mml:mo></mml:mrow></mml:math></inline-formula>, where &#x003C3;<sub>(&#x003B5;)</sub> &#x0003D; <italic>t</italic><sub><italic>x</italic><sub>1</sub></sub> <italic>t</italic><sub><italic>x</italic><sub>2</sub></sub> &#x022EF; <italic>t</italic><sub><italic>x</italic><sub>&#x003B5;</sub></sub>, and <italic>t</italic><sub><italic>x</italic><sub>1</sub></sub>, <italic>t</italic><sub><italic>x</italic><sub>2</sub></sub>, &#x022EF;&#x02009;, <italic>t</italic><sub><italic>x</italic><sub>&#x003B5;</sub></sub> &#x02208; <italic>T</italic>.</p>
<p>Based on the above definitions, <italic>weak behavioral profile</italic> between two transitions is shown in the following.</p>
<p><bold>Definition 3</bold> [Weak behavioral profile, bp (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>)]. Given a WF-net system (<italic>N, M</italic><sub>0</sub>) &#x0003D; (<italic>P, T, F, M</italic><sub>0</sub>), a pair of transitions <italic>t</italic><sub><italic>x</italic></sub>, <italic>t</italic><sub><italic>y</italic></sub> &#x02208; <italic>T</italic> is in one of the following relations, where <italic>k</italic> &#x02208; {1, 3, &#x022EF;&#x02009;, <italic>n</italic>}, <italic>n</italic> &#x0003D; 2<italic>m</italic> &#x02212; 1, and <italic>m</italic> &#x02208; &#x02115;:</p>
<list list-type="order">
<list-item><p>Weak strict order relation (<italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>), if (<italic>t</italic><sub><italic>x</italic></sub> &#x0227B;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; (<italic>t</italic><sub><italic>y</italic></sub> &#x02281;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>x</italic></sub>);</p></list-item>
<list-item><p>Weak exclusiveness relation (<italic>t</italic><sub><italic>x</italic></sub> &#x0002B;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>), if (<italic>t</italic><sub><italic>x</italic></sub> &#x02281;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; (<italic>t</italic><sub><italic>y</italic></sub> &#x02281;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>x</italic></sub>); or</p></list-item>
<list-item><p>Weak interleaving order relation (<italic>t</italic><sub><italic>x</italic></sub> &#x02225;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>), if (<italic>t</italic><sub><italic>x</italic></sub> &#x0227B;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; (<italic>t</italic><sub><italic>y</italic></sub> &#x0227B;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>x</italic></sub>). It contains the following two kinds:</p>
<list list-type="order">
<list-item><p>Weak circulation relation (<italic>t</italic><sub><italic>x</italic></sub> &#x02194;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>), if <inline-formula><mml:math id="M7"><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mo>&#x0227B;</mml:mo></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>&#x02227;</mml:mo><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mo>&#x0227B;</mml:mo></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>&#x02227;</mml:mo><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msubsup><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x02229;</mml:mo><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msubsup><mml:mrow><mml:mo>&#x0222A;</mml:mo></mml:mrow><mml:mrow><mml:mi>k</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mi>n</mml:mi></mml:mrow></mml:msubsup><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mi>k</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:msup><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>&#x02260;</mml:mo><mml:mo class="MathClass-ord">&#x02205;</mml:mo></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>&#x02227;</mml:mo><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msubsup><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x02229;</mml:mo><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msubsup><mml:mrow><mml:mo>&#x0222A;</mml:mo></mml:mrow><mml:mrow><mml:mi>k</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mi>n</mml:mi></mml:mrow></mml:msubsup><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mi>k</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:msup><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>&#x02260;</mml:mo><mml:mo class="MathClass-ord">&#x02205;</mml:mo></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math></inline-formula>; or</p></list-item>
<list-item><p>Weak concurrency relation (<italic>t</italic><sub><italic>x</italic></sub> &#x021C4;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>), if <inline-formula><mml:math id="M8"><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mo>&#x0227B;</mml:mo></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>&#x02227;</mml:mo><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mo>&#x0227B;</mml:mo></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>&#x02227;</mml:mo><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msubsup><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x02229;</mml:mo><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msubsup><mml:mrow><mml:mo>&#x0222A;</mml:mo></mml:mrow><mml:mrow><mml:mi>k</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mi>n</mml:mi></mml:mrow></mml:msubsup><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mi>k</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:msup><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>=</mml:mo><mml:mo class="MathClass-ord">&#x02205;</mml:mo></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>&#x02227;</mml:mo><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msubsup><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x02229;</mml:mo><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msubsup><mml:mrow><mml:mo>&#x0222A;</mml:mo></mml:mrow><mml:mrow><mml:mi>k</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mi>n</mml:mi></mml:mrow></mml:msubsup><mml:msup><mml:mrow><mml:mtext>&#x000A0;</mml:mtext></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mi>k</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:msup><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>=</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:mo class="MathClass-ord">&#x02205;</mml:mo></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math></inline-formula>.</p></list-item>
</list></list-item></list>
<p>The above relations comprise the weak behavioral profile of (<italic>N, M</italic><sub>0</sub>), denoted as <italic>bp</italic> &#x0003D; {<italic>bp</italic><sub>1</sub>, <italic>bp</italic><sub>2</sub>, <italic>bp</italic><sub>3</sub>}, where <italic>bp</italic><sub>1</sub> &#x0003D; &#x02192;<sub><italic>c</italic></sub>, <italic>bp</italic><sub>2</sub> &#x0003D; &#x0002B;<sub><italic>c</italic></sub>, and <italic>bp</italic><sub>3</sub> &#x0003D; &#x02225;<sub><italic>c</italic></sub>. As for the inverse order relation of <italic>bp</italic><sub>1</sub> [i.e., (<italic>t</italic><sub><italic>x</italic></sub> &#x02281;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; (<italic>t</italic><sub><italic>y</italic></sub> &#x0227B;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>x</italic></sub>)], we denote it as <inline-formula><mml:math id="M9"><mml:msubsup><mml:mrow><mml:mo>&#x02192;</mml:mo></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow></mml:msubsup></mml:math></inline-formula> or <italic>bp</italic><sub>&#x02212;1</sub>. If <italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>, then we have <inline-formula><mml:math id="M10"><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub><mml:msubsup><mml:mrow><mml:mo>&#x02192;</mml:mo></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow></mml:msubsup><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:math></inline-formula> or (<italic>t</italic><sub><italic>y</italic></sub>, <italic>t</italic><sub><italic>x</italic></sub>) &#x0003D; <italic>bp</italic><sub>&#x02212;1</sub>. The weak behavioral profile relation is also called weak behavioral relation in this paper. In <xref ref-type="fig" rid="F1">Figure 1A</xref>, we have <italic>t</italic><sub>1</sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub>2</sub>, <italic>t</italic><sub>3</sub> &#x0002B;<sub><italic>c</italic></sub> <italic>t</italic><sub>4</sub>, and <italic>t</italic><sub>3</sub> &#x02225;<sub><italic>c</italic></sub> <italic>t</italic><sub>5</sub>. They are denoted as (<italic>t</italic><sub>1</sub>, <italic>t</italic><sub>2</sub>) &#x0003D; <italic>bp</italic><sub>1</sub>, (<italic>t</italic><sub>3</sub>, <italic>t</italic><sub>4</sub>) &#x0003D; <italic>bp</italic><sub>2</sub>, and (<italic>t</italic><sub>3</sub>, <italic>t</italic><sub>5</sub>) &#x0003D; <italic>bp</italic><sub>3</sub>, respectively.</p>
<p>A workflow net with data (<italic>WFD-net</italic>) is a WF-net with every transition <italic>t</italic> &#x02208; <italic>T</italic> labeled with four elements at most:
<list list-type="order">
<list-item><p>Some data items need to be read before firing <italic>t</italic>;</p></list-item>
<list-item><p>Some data items would be written after firing <italic>t</italic>;</p></list-item>
<list-item><p>Some data items may be deleted after firing <italic>t</italic>;</p></list-item>
<list-item><p>Some data items may be the guard functions of <italic>t</italic> (optional).</p></list-item>
</list></p>
<p>The update of data items can be seen as the combination of read/write operations on transitions. Furthermore, writing a data item on a transition for the first time can be known as creating the data item. We also assume that there are no read operations or guard functions on the initial transition (Trcka et al., <xref ref-type="bibr" rid="B25">2009</xref>; Sidorova et al., <xref ref-type="bibr" rid="B19">2011</xref>).</p>
<p><bold>Definition 4</bold> [WFD-net (Trcka et al., <xref ref-type="bibr" rid="B25">2009</xref>; Sidorova et al., <xref ref-type="bibr" rid="B19">2011</xref>)]. A WFD-net <italic>ND</italic> &#x0003D; (<italic>P, T, F, D, Guard, R, W, De, Gd</italic>) is a workflow net (WF-net) extended with data, it consists of the following:</p>
<list list-type="order">
<list-item><p>(<italic>P, T, F</italic>) is a WF-net;</p></list-item>
<list-item><p><italic>D</italic> is a different set of data items;</p></list-item>
<list-item><p><italic>Guard</italic> is a set of guards over <italic>D</italic>;</p></list-item>
<list-item><p><italic>R</italic> : <italic>T</italic> &#x02192; 2<sup><italic>D</italic></sup> is the read operation set;</p></list-item>
<list-item><p><italic>W</italic> : <italic>T</italic> &#x02192; 2<sup><italic>D</italic></sup> is the write operation set;</p></list-item>
<list-item><p><italic>De</italic> : <italic>T</italic> &#x02192; 2<sup><italic>D</italic></sup> is the delete operation set; and</p></list-item>
<list-item><p><italic>Gd</italic> : <italic>T</italic> &#x02192; <italic>Guard</italic> is a function that assign guards to transitions.</p></list-item>
</list>
<p>A WFD-net system is a WFD-net with an initial marking <italic>M</italic><sub>0</sub>, it can be denoted as (<italic>ND, M</italic><sub>0</sub>) &#x0003D; (<italic>P, T, F, M</italic><sub>0</sub>, <italic>D, Guard, R, W, De, Gd</italic>). In the following, all workflow systems are in the form of WFD-net systems. <xref ref-type="fig" rid="F1">Figures 1A</xref>, <xref ref-type="fig" rid="F1">B</xref> depict two WFD-net systems.</p></sec>
<sec>
<title>2.2. Motivating example</title>
<p>This subsection takes two <italic>shipper process models</italic> as a motivating example to illustrate our work, as shown in <xref ref-type="fig" rid="F1">Figures 1A</xref>, <xref ref-type="fig" rid="F1">B</xref>. There are 5 same data items in these figures (i.e., <italic>cus, gds, des, price</italic>, and <italic>bon</italic>, where <italic>cus</italic> denotes the data of customers, <italic>gds</italic> stands for the data of goods, <italic>des</italic> represents the destination of goods, <italic>price</italic> means the price of goods, and <italic>bon</italic> denotes the bonus), and the set of guards is <italic>Guard</italic> &#x0003D; {<italic>isHigh</italic>(<italic>price</italic>), &#x000AC;<italic>isHigh</italic>(<italic>price</italic>)}. For the transition <italic>t</italic><sub>5</sub>, its data operations and guard function are <italic>R</italic>(<italic>t</italic><sub>5</sub>) &#x0003D; {<italic>price</italic>}, <italic>W</italic>(<italic>t</italic><sub>5</sub>) &#x0003D; {<italic>bon</italic>}, <italic>De</italic>(<italic>t</italic><sub>5</sub>) &#x0003D; &#x02205;, and <italic>Gd</italic>(<italic>t</italic><sub>5</sub>) &#x0003D; {<italic>isHigh</italic>(<italic>price</italic>)}, respectively.</p>
<p><xref ref-type="fig" rid="F1">Figure 1A</xref> describes a shipper process model in the shape of a WFD-net system. Firstly, shippers receive goods from customers and write 3 data items, i.e., the data of customers and goods, and the destination of goods. Then, shippers should calculate the price by reading the data of goods and generating the price. Afterwards, customer advisers and shipment departments execute their tasks concurrently. If the goods&#x00027; price is high, express shipment is used by reading the data of goods and the destination of the goods. Under the same condition, customer advisors calculate the bonus for customers by reading the price and producing the bonus. If the price of goods is not high, normal shipment is taken by reading the data of goods and the destination of goods, and there is no bonus to calculate. If the customer advisors calculate the bonus for customers, then they should register the bonus by reading the data of customers and the bonus as well as generating new data of customers. At last, customers who send goods are informed by call.</p>
<p><xref ref-type="fig" rid="F1">Figure 1B</xref> shows a similar model to <xref ref-type="fig" rid="F1">Figure 1A</xref>. However, there are some extra transitions (i.e., <italic>t</italic><sub>9</sub> and <italic>t</italic><sub>10</sub>) and data items (i.e., <italic>d</italic><sub><italic>q</italic></sub>) without any correspondences in <xref ref-type="fig" rid="F1">Figure 1B</xref>. The transition <italic>t</italic><sub>9</sub> represents <italic>Review Goods</italic>, the transition <italic>t</italic><sub>10</sub> denotes <italic>Confirm Goods</italic>, and the data item <italic>d</italic><sub><italic>q</italic></sub> stands for <italic>the quality of the goods</italic>.</p>
<p>The method of DTC ignores those transitions without correspondence, e.g., <italic>t</italic><sub>9</sub> and <italic>t</italic><sub>10</sub> in <xref ref-type="fig" rid="F1">Figure 1B</xref>. Therefore, the method of DTC is insensitive to these extended elements, and the trace consistency degree of <xref ref-type="fig" rid="F1">Figures 1A</xref>, <xref ref-type="fig" rid="F1">B</xref> computed by this method is 1. This result means that the traces in the above figures are the same. However, these extensions may produce data dependencies (cf. Def. 6) and affect the real traces. Therefore, the DTC method may be inappropriate for analyzing the real trace consistency degrees of WFD-net systems.</p></sec></sec>
<sec id="s3">
<title>3. Trace consistency measurement based on data and behavioral profiles</title>
<p>Before introducing <italic>the trace consistency degree of two WFD-net systems</italic>, we present <italic>control dependency</italic> and <italic>data dependency</italic> of transition pairs in this section. Then, we illustrate trace and trace consistency degree.</p>
<p><bold>Definition 5</bold> (Control dependency). Given two transitions <italic>t</italic><sub><italic>x</italic></sub> and <italic>t</italic><sub><italic>y</italic></sub> in (<italic>ND, M</italic><sub>0</sub>), <italic>t</italic><sub><italic>y</italic></sub>is control-dependent on <italic>t</italic><sub><italic>x</italic></sub> if <italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>.</p>
<p>When the specific read/delete operation of a transition is derived from the write operation of another transition, we say there exists a data dependency. The data dependency may affect the traces in a model. The specific details are shown as follows.</p>
<p><bold>Definition 6</bold> (Data dependency). Given two transitions <italic>t</italic><sub><italic>x</italic></sub> and <italic>t</italic><sub><italic>y</italic></sub> in (<italic>ND, M</italic><sub>0</sub>), <italic>t</italic><sub><italic>y</italic></sub> is data-dependent on <italic>t</italic><sub><italic>x</italic></sub> (i.e., <italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) if:
<list list-type="order">
<list-item><p>There exists a data item <italic>d</italic> &#x02208; <italic>D</italic>:[<italic>d</italic> &#x02208; <italic>W</italic>(<italic>t</italic><sub><italic>x</italic></sub>) &#x02229; (<italic>R</italic>(<italic>t</italic><sub><italic>y</italic></sub>) &#x0222A; <italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>))] &#x02227; [<italic>d</italic> &#x02209; <italic>De</italic>(<italic>t</italic><sub><italic>x</italic></sub>)]; and</p></list-item>
<list-item><p>There is no transition <italic>t</italic><sub><italic>w</italic></sub> enabled between <italic>t</italic><sub><italic>x</italic></sub> and <italic>t</italic><sub><italic>y</italic></sub>, such that <italic>d</italic> &#x02208; <italic>W</italic>(<italic>t</italic><sub><italic>w</italic></sub>) &#x0222A; <italic>De</italic>(<italic>t</italic><sub><italic>w</italic></sub>).</p></list-item>
</list></p>
<p>Let <italic>t</italic><sub><italic>x</italic></sub> and <italic>t</italic><sub><italic>y</italic></sub> be a pair of transitions derived from (<italic>ND, M</italic><sub>0</sub>). The control dependency indicates there is a weak strict order relation such that <italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>. In <xref ref-type="fig" rid="F1">Figures 1A</xref>, <xref ref-type="fig" rid="F1">B</xref>, we have <italic>t</italic><sub>1</sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub>2</sub>. The control dependency satisfies the transitivity. That is, if (<italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; (<italic>t</italic><sub><italic>y</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>r</italic></sub>), then we have <italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>r</italic></sub>. A transition <italic>t</italic><sub><italic>y</italic></sub> is data-dependent on another transition <italic>t</italic><sub><italic>x</italic></sub> implies that <italic>t</italic><sub><italic>y</italic></sub> reads/deletes a data item written by <italic>t</italic><sub><italic>x</italic></sub>. If there is no data dependency between <italic>t</italic><sub><italic>x</italic></sub> and <italic>t</italic><sub><italic>y</italic></sub>, then we have <italic>t</italic><sub><italic>x</italic></sub> &#x02225;<sub><italic>d</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>. In <xref ref-type="fig" rid="F1">Figure 1B</xref>, <italic>t</italic><sub>10</sub> is data-dependent on <italic>t</italic><sub>9</sub> as <italic>d</italic><sub><italic>q</italic></sub> &#x02208; <italic>W</italic>(<italic>t</italic><sub>9</sub>) &#x02229; <italic>R</italic>(<italic>t</italic><sub>10</sub>) and there is no transition <italic>t</italic><sub><italic>w</italic></sub> enabled between <italic>t</italic><sub>9</sub> and <italic>t</italic><sub>10</sub>, such that <italic>d</italic><sub><italic>q</italic></sub> &#x02208; <italic>W</italic>(<italic>t</italic><sub><italic>w</italic></sub>) &#x02229; <italic>De</italic>(<italic>t</italic><sub><italic>w</italic></sub>).</p>
<p><bold>Definition 7</bold> [Distance between transitions in weak circulation relation (Zhao et al., <xref ref-type="bibr" rid="B40">2022a</xref>)]. Let (<italic>ND, M</italic><sub>0</sub>) &#x0003D; (<italic>P, T, F, M</italic><sub>0</sub>, <italic>D, Guard, R, W, De, Gd</italic>) be a WFD-net system, <inline-formula><mml:math id="M11"><mml:mo>&#x02203;</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub><mml:mo>&#x02208;</mml:mo><mml:mi>T</mml:mi><mml:mo>:</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mo>&#x02194;</mml:mo></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mo>&#x02208;</mml:mo><mml:msup><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mi>k</mml:mi><mml:mn>1</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:msup></mml:math></inline-formula>, and <inline-formula><mml:math id="M12"><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub><mml:mo>&#x02208;</mml:mo><mml:msup><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mo>&#x000B7;</mml:mo></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mi>k</mml:mi><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:msup></mml:math></inline-formula>, where <italic>t</italic> is a transition outside the weak circulation relation with <italic>t</italic><sub><italic>x</italic></sub> and <italic>t</italic><sub><italic>y</italic></sub>, <italic>k</italic><sub>1</sub> and <italic>k</italic><sub>2</sub> are the minimum number of post-sets, such that <italic>k</italic><sub>1</sub>, <italic>k</italic><sub>2</sub> &#x02208; {2, 4, &#x022EF;&#x02009;, 2<italic>m</italic>}, and <italic>m</italic> &#x02208; &#x02115;. The distance between <italic>t</italic><sub><italic>x</italic></sub> and <italic>t</italic><sub><italic>y</italic></sub> is defined as &#x003B4;[<italic>t</italic><sub><italic>y</italic></sub>, <italic>t</italic><sub><italic>x</italic></sub>] &#x0003D; <italic>k</italic><sub>2</sub> &#x02212; <italic>k</italic><sub>1</sub>.</p>
<p>For the example of <xref ref-type="fig" rid="F2">Figure 2A</xref>, we have <italic>t</italic><sub><italic>x</italic></sub> &#x02194;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>, and &#x003B4;[<italic>t</italic><sub><italic>y</italic></sub>, <italic>t</italic><sub><italic>x</italic></sub>] &#x0003D; <italic>k</italic><sub>2</sub> &#x02212; <italic>k</italic><sub>1</sub> &#x0003D; 2.</p>
<fig id="F2" position="float">
<label>Figure 2</label>
<caption><p><bold>(A)</bold> <italic>t</italic><sub><italic>x</italic></sub> and <italic>t</italic><sub><italic>y</italic></sub> are in weak circulation relation (i.e., <italic>t</italic><sub><italic>x</italic></sub> &#x02194;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>); <bold>(B, C)</bold> The behavioral relation of <italic>t</italic><sub><italic>x</italic></sub> and <italic>t</italic><sub><italic>y</italic></sub> depends on their guard functions.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fcomp-05-1136057-g0002.tif"/>
</fig>
<sec>
<title>3.1. Transition pairs behavioral relations in a WFD-net system</title>
<p>Before formalizing the relation of transitions <italic>t</italic><sub><italic>x</italic></sub> and <italic>t</italic><sub><italic>y</italic></sub> in a WFD-net system, we first explain some relevant symbols as follows:
<list list-type="order">
<list-item><p><italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>)) (resp. <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>))) is the set of data items in guards related to <italic>t</italic><sub><italic>x</italic></sub> (resp. <italic>t</italic><sub><italic>y</italic></sub>), and <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>))) (resp. <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>)))) is the value of <italic>d</italic> in guards related to <italic>t</italic><sub><italic>x</italic></sub> (resp. <italic>t</italic><sub><italic>y</italic></sub>); and</p></list-item>
<list-item><p>&#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>))) (resp. &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)))) is the set of final values of data items in <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>))(resp. <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>))), and &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>))))(resp. &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>)))) is the final value of <italic>d</italic> in <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>))(resp. <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>))).</p></list-item>
</list></p>
<p>For the transition <italic>t</italic><sub><italic>y</italic></sub> in <xref ref-type="fig" rid="F2">Figure 2C</xref>, we have</p>
<list list-type="order">
<list-item><p><italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)) is {<italic>a, b</italic>}, and <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>a</italic>)))(resp. <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>b</italic>))) is <italic>a</italic> &#x0003E; 0 (resp. <italic>b</italic> &#x02264; 0) in guards related to <italic>t</italic><sub><italic>y</italic></sub>; and</p></list-item>
<list-item><p>&#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>))) is the set of final values of {<italic>a, b</italic>} in <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)), and &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>a</italic>))))(resp. &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>b</italic>)))) is <italic>a</italic> &#x0003D; 3 (resp. <italic>b</italic> &#x0003D; 5 &#x02212; 4 &#x0003D; 1) in <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)).</p></list-item>
</list>
<p>The transition pairs&#x00027; behavioral relations in a WFD-net system depend on their weak behavioral relations, data dependencies, and guard functions. The following behavioral relations compose the <italic>behavioral profile</italic> of a WFD-net system.</p>
<p><bold>Definition 8</bold> (Behavioral profile, BP). Given a WFD-net system (<italic>ND, M</italic><sub>0</sub>) &#x0003D; (<italic>P, T, F, M</italic><sub>0</sub>, <italic>D, Guard, R, W, De, Gd</italic>) and a pair of transitions <italic>t</italic><sub><italic>x</italic></sub>,<italic>t</italic><sub><italic>y</italic></sub> &#x02208; <italic>T</italic>, we have</p>
<list list-type="order">
<list-item><p>Strict order relation (<italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>), if</p>
<list list-type="order">
<list-item><p>(<italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; [(<italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>d</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02228; (<italic>t</italic><sub><italic>x</italic></sub> &#x02225;<sub><italic>d</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>)]; or</p></list-item>
<list-item><p>(<italic>t</italic><sub><italic>x</italic></sub> &#x021C4;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; (<italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>d</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>).</p></list-item>
</list></list-item>
<list-item><p>Exclusiveness relation (<italic>t</italic><sub><italic>x</italic></sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>), if</p>
<list list-type="order">
<list-item><p>(<italic>t</italic><sub><italic>x</italic></sub> &#x0002B;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; (<italic>t</italic><sub><italic>x</italic></sub> &#x02225;<sub><italic>d</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>);</p></list-item>
<list-item><p>If (<italic>t</italic><sub><italic>x</italic></sub> &#x02225;<sub><italic>d</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02228; (<italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02228; (<italic>t</italic><sub><italic>y</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>x</italic></sub>), &#x02203;<italic>d</italic>:<italic>d</italic> &#x02208; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>)) &#x02229; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)), and [<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>))) &#x02229; &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>)))) &#x0003D; &#x02205;] &#x02228; [<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>))) &#x02229;</p>
<p>&#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>)))) &#x0003D; &#x02205;];</p></list-item>
<list-item><p>If <italic>t</italic><sub><italic>x</italic></sub> &#x021C4;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>, &#x02203;<italic>d</italic>:<italic>d</italic> &#x02208; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>)) &#x02229; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)), and <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>))) &#x02229; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>))) &#x0003D; &#x02205;.</p>
<p>or</p></list-item></list></list-item>
<list-item><p>Interleaving order relation (<italic>t</italic><sub><italic>x</italic></sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>). It can be divided into the following two kinds:</p>
<list list-type="order">
<list-item><p>Circulation relation (<italic>t</italic><sub><italic>x</italic></sub> &#x02194;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>), if (<italic>t</italic><sub><italic>x</italic></sub> &#x02194;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; [(<italic>t</italic><sub><italic>x</italic></sub> &#x02225;<sub><italic>d</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02228; ((&#x003B4;[<italic>t</italic><sub><italic>y</italic></sub>, <italic>t</italic><sub><italic>x</italic></sub>] &#x02265; 0) &#x02227; (<italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>d</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>))]; or</p></list-item>
<list-item><p>Concurrency relation (<italic>t</italic><sub><italic>x</italic></sub> &#x021C4;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>), if</p>
<list list-type="roman-lower">
<list-item><p><italic>t</italic><sub><italic>x</italic></sub> &#x021C4;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub> and &#x02204;<italic>d</italic>:<italic>d</italic> &#x02208; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>)) &#x02229; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)); or</p></list-item>
<list-item><p><italic>t</italic><sub><italic>x</italic></sub> &#x021C4;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>, <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>)) &#x02229; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)) &#x0003D; {&#x1D507;}, and &#x02200;<italic>d</italic> &#x02208; &#x1D507;:[<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>))) &#x02229; &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>)))) &#x02260; &#x02205;] &#x02227; [<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>))) &#x02229; &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>)))) &#x02260; &#x02205;]&#x000B0;</p></list-item>
</list>
</list-item></list>
</list-item></list>
<p>These relations constitute the behavioral profile of (<italic>ND, M</italic><sub>0</sub>), denoted as <italic>BP</italic> &#x0003D; {<italic>BP</italic><sub>1</sub>, <italic>BP</italic><sub>2</sub>, <italic>BP</italic><sub>3</sub>}, where <italic>BP</italic><sub>1</sub> &#x0003D; &#x02192;<sub><italic>cd</italic></sub>, <italic>BP</italic><sub>2</sub> &#x0003D; &#x0002B;<sub><italic>cd</italic></sub>, and <italic>BP</italic><sub>3</sub> &#x0003D; &#x02225;<sub><italic>cd</italic></sub>. We use <italic>BP</italic><sub>&#x02212;1</sub> or <inline-formula><mml:math id="M13"><mml:msubsup><mml:mrow><mml:mo>&#x02192;</mml:mo></mml:mrow><mml:mrow><mml:mi>c</mml:mi><mml:mi>d</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msubsup></mml:math></inline-formula> to show the inverse order relation of <italic>BP</italic><sub>1</sub>. It&#x00027;s worth noting that each transition pair can be in a single behavioral relation.</p>
<p>As we know, <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub>3</sub>(<italic>price</italic>))) &#x0003D; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub>5</sub>(<italic>price</italic>))) &#x0003D; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub>6</sub>(<italic>price</italic>))) &#x0003D; {[<italic>isHigh</italic>(<italic>price</italic>)]} and <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub>4</sub>(<italic>price</italic>))) &#x0003D; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub>7</sub>(<italic>price</italic>))) &#x0003D; {[&#x000AC;<italic>isHigh</italic>(<italic>price</italic>)]}. Therefore, we have <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub>3</sub>(<italic>price</italic>))) &#x02229; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub>7</sub>(<italic>price</italic>))) &#x0003D; &#x02205;, <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub>4</sub>(<italic>price</italic>))) &#x02229; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub>5</sub>(<italic>price</italic>))) &#x0003D; &#x02205;, and <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub>4</sub>(<italic>price</italic>))) &#x02229; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub>6</sub>(<italic>price</italic>))) &#x0003D; &#x02205;. According to Def. 8, we have (<italic>t</italic><sub>3</sub>, <italic>t</italic><sub>7</sub>) &#x0003D; (<italic>t</italic><sub>4</sub>, <italic>t</italic><sub>5</sub>) &#x0003D; (<italic>t</italic><sub>4</sub>, <italic>t</italic><sub>6</sub>) &#x0003D; <italic>BP</italic><sub>2</sub>, and (<italic>t</italic><sub>3</sub>, <italic>t</italic><sub>5</sub>) &#x0003D; (<italic>t</italic><sub>4</sub>, <italic>t</italic><sub>7</sub>) &#x0003D; <italic>BP</italic><sub>3</sub> in <xref ref-type="fig" rid="F1">Figures 1A</xref>, <xref ref-type="fig" rid="F1">B</xref> after taking these guard functions into consideration. Without considering data dependencies of transitions without correspondences, we have (<italic>t</italic><sub>3</sub>, <italic>t</italic><sub>6</sub>) &#x0003D; <italic>BP</italic><sub>3</sub> in <xref ref-type="fig" rid="F1">Figures 1A</xref>, <xref ref-type="fig" rid="F1">B</xref>. After considering the data item <italic>d</italic><sub><italic>q</italic></sub>, we know <italic>d</italic><sub><italic>q</italic></sub> &#x02208; <italic>W</italic>(<italic>t</italic><sub>9</sub>) &#x02229; <italic>R</italic>(<italic>t</italic><sub>10</sub>), and <italic>t</italic><sub>9</sub> &#x02192;<sub><italic>cd</italic></sub> <italic>t</italic><sub>10</sub> as <italic>t</italic><sub>10</sub> is data-dependent on <italic>t</italic><sub>9</sub> in <xref ref-type="fig" rid="F1">Figure 1B</xref>. Therefore, we have (<italic>t</italic><sub>3</sub>, <italic>t</italic><sub>6</sub>) &#x0003D; <italic>BP</italic><sub>3</sub> in <xref ref-type="fig" rid="F1">Figure 1A</xref> and (<italic>t</italic><sub>3</sub>, <italic>t</italic><sub>6</sub>) &#x0003D; <italic>BP</italic><sub>1</sub> in <xref ref-type="fig" rid="F1">Figure 1B</xref>. In <xref ref-type="fig" rid="F2">Figure 2B</xref>, if there exists no data item <italic>d</italic> satisfying <italic>d</italic> &#x02208; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>)) &#x02229; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)), then we have <italic>t</italic><sub><italic>x</italic></sub> &#x021C4;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>.</p>
<p><bold>Definition 9</bold> (Order relation). Let (<italic>ND, M</italic><sub>0</sub>) &#x0003D; (<italic>P, T, F, M</italic><sub>0</sub>, <italic>D, Guard, R, W, De, Gd</italic>) be a WFD-net system, the order relation <italic>t</italic><sub><italic>x</italic></sub> &#x0227B; <italic>t</italic><sub><italic>y</italic></sub> includes transitions <italic>t</italic><sub><italic>x</italic></sub> and <italic>t</italic><sub><italic>y</italic></sub> satisfying one of the following conditions:
<list list-type="order">
<list-item><p><italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>;</p></list-item>
<list-item><p><italic>t</italic><sub><italic>x</italic></sub> &#x021C4;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>;</p></list-item>
<list-item><p>(<italic>t</italic><sub><italic>x</italic></sub> &#x02194;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; (&#x003B4;[<italic>t</italic><sub><italic>y</italic></sub>, <italic>t</italic><sub><italic>x</italic></sub>]&#x02265; 0).</p></list-item>
</list></p>
<p>If some transitions lack data dependencies, there is a <italic>missing data</italic>. Based on the above relation, we further formalize missing data.</p>
<p><bold>Definition 10</bold> (Missing data, MD). Given a WFD-net system (<italic>ND, M</italic><sub>0</sub>) &#x0003D; (<italic>P, T, F, M</italic><sub>0</sub>, <italic>D, Guard</italic>, <italic>R, W, De, Gd</italic>), <italic>T</italic><sup>&#x0002A;</sup> is the set of all weak firing subsequences, &#x02203;&#x003C3; &#x02208; <italic>T</italic><sup>&#x0002A;</sup>, and <inline-formula><mml:math id="M14"><mml:mo>&#x02203;</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>m</mml:mi></mml:mrow></mml:msub><mml:mo>&#x02208;</mml:mo><mml:mi>&#x003C3;</mml:mi><mml:mo>:</mml:mo><mml:msub><mml:mrow><mml:mi>p</mml:mi></mml:mrow><mml:mrow><mml:mi>i</mml:mi></mml:mrow></mml:msub><mml:mo>&#x02208;</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>m</mml:mi></mml:mrow></mml:msub></mml:math></inline-formula>. A data item <italic>d</italic> &#x02208; <italic>D</italic> is missing if one of the following conditions is satisfied:
<list list-type="order">
<list-item><p>&#x02203;<italic>t</italic><sub><italic>y</italic></sub> &#x02208; <italic>T</italic>, &#x02200;<italic>t</italic><sub><italic>x</italic></sub> &#x02208; &#x003C3;:(<italic>t</italic><sub><italic>x</italic></sub> &#x0227B; <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; [((<italic>d</italic> &#x02209; <italic>W</italic>(<italic>t</italic><sub><italic>x</italic></sub>)) &#x02227; (<italic>d</italic> &#x02208; <italic>De</italic>(<italic>t</italic><sub><italic>x</italic></sub>) &#x0222A; <italic>R</italic>(<italic>t</italic><sub><italic>y</italic></sub>))) &#x02228; ((<italic>d</italic> &#x02209; <italic>W</italic>(<italic>t</italic><sub><italic>x</italic></sub>) &#x0222A; <italic>W</italic>(<italic>t</italic><sub><italic>y</italic></sub>)) &#x02227; (<italic>d</italic> &#x02208; <italic>De</italic>(<italic>t</italic><sub><italic>y</italic></sub>)))], which is denoted by <italic>d</italic> &#x022D6; <italic>MD</italic>; or</p></list-item>
<list-item><p>&#x02203;<italic>t</italic><sub><italic>x</italic></sub> &#x02208; &#x003C3;, &#x02203;<italic>t</italic><sub><italic>z</italic></sub> &#x02208; <italic>T</italic>, &#x02200; <italic>t</italic><sub><italic>y</italic></sub> &#x02208; <italic>T</italic>:(<italic>t</italic><sub><italic>x</italic></sub> &#x0227B; <italic>t</italic><sub><italic>z</italic></sub>) &#x02227; (<italic>t</italic><sub><italic>x</italic></sub> &#x0227B; <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; (<italic>t</italic><sub><italic>y</italic></sub> &#x0227B; <italic>t</italic><sub><italic>z</italic></sub>) &#x02227; [<italic>d</italic> &#x02208; <italic>W</italic>(<italic>t</italic><sub><italic>x</italic></sub>) &#x02229; (<italic>De</italic>(<italic>t</italic><sub><italic>x</italic></sub>) &#x0222A; <italic>De</italic>(<italic>t</italic><sub><italic>y</italic></sub>)) &#x02229; (<italic>R</italic>(<italic>t</italic><sub><italic>z</italic></sub>) &#x0222A; <italic>De</italic>(<italic>t</italic><sub><italic>z</italic></sub>))] &#x02227; (<italic>d</italic> &#x02276; <italic>R</italic>(<italic>t</italic><sub><italic>y</italic></sub>)) &#x02227; [<italic>d</italic> &#x02209; <italic>W</italic>(<italic>t</italic><sub><italic>y</italic></sub>) &#x0222A; <italic>W</italic>(<italic>t</italic><sub><italic>z</italic></sub>)], which is denoted by <italic>d</italic> &#x022D6; <italic>MD</italic>, where <italic>d</italic> &#x02276; <italic>R</italic>(<italic>t</italic><sub><italic>y</italic></sub>) denotes <italic>d</italic> &#x02208; <italic>R</italic>(<italic>t</italic><sub><italic>y</italic></sub>) or <italic>d</italic> &#x02209; <italic>R</italic>(<italic>t</italic><sub><italic>y</italic></sub>).</p></list-item>
</list></p>
<p>A missing data appears when a data item is read or deleted but not written before (Meda et al., <xref ref-type="bibr" rid="B15">2010</xref>), as shown in <xref ref-type="fig" rid="F3">Figures 3A</xref>&#x02013;<xref ref-type="fig" rid="F3">D</xref>. This error may affect the trace (Def. 12) in a WFD-net system. If the missing data is not an ending error, we can analyze the trace consistency of two WFD-net systems. As shown in <xref ref-type="fig" rid="F3">Figure 3B</xref>, we have <italic>t</italic><sub>3</sub> &#x02192;<sub><italic>cd</italic></sub> <italic>t</italic><sub>2</sub> as <italic>t</italic><sub>2</sub> is data-dependent on <italic>t</italic><sub>3</sub>.</p>
<fig id="F3" position="float">
<label>Figure 3</label>
<caption><p><italic>d</italic> is a missing data in <bold>(A&#x02013;D)</bold>.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fcomp-05-1136057-g0003.tif"/>
</fig>
<p>Notice that, if [(<italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; (<italic>t</italic><sub><italic>y</italic></sub> &#x02192;<sub><italic>d</italic></sub> <italic>t</italic><sub><italic>x</italic></sub>)] &#x02228; [(<italic>t</italic><sub><italic>x</italic></sub> &#x0002B;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; ((<italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>d</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02228; (<italic>t</italic><sub><italic>y</italic></sub> &#x02192;<sub><italic>d</italic></sub> <italic>t</italic><sub><italic>x</italic></sub>))] &#x02228; [(<italic>t</italic><sub><italic>x</italic></sub> &#x02194;<sub><italic>c</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>) &#x02227; (&#x003B4;[<italic>t</italic><sub><italic>y</italic></sub>, <italic>t</italic><sub><italic>x</italic></sub>] &#x0003E; 0) &#x02227; (<italic>t</italic><sub><italic>y</italic></sub> &#x02192;<sub><italic>d</italic></sub> <italic>t</italic><sub><italic>x</italic></sub>)], there is a missing data. When the missing data is an ending error, there is no point in analyzing the traces in two WFD-net models.</p></sec>
<sec>
<title>3.2. Firing sequence and traces in a WFD-net System</title>
<p>Before defining the <italic>trace</italic>, we present the definition of <italic>firing sequence</italic>.</p>
<p><bold>Definition 11</bold> (Firing sequence). Given a WFD-net system (<italic>ND, M</italic><sub>0</sub>) &#x0003D; (<italic>P, T, F, M</italic><sub>0</sub>, <italic>D, Guard</italic>, <italic>R, W, De, Gd</italic>), &#x003C3;<sub><italic>i</italic></sub> &#x0003D; <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub> &#x022EF; <italic>t</italic><sub><italic>n</italic></sub>(<italic>n</italic> &#x02208; &#x02115;) is a firing sequence in (<italic>ND, M</italic><sub>0</sub>) if</p>
<list list-type="order">
<list-item><p><italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>, where 1 &#x02264; <italic>x</italic> &#x0003C; <italic>y</italic> &#x02264; <italic>n</italic>; or</p></list-item>
<list-item><p><italic>t</italic><sub><italic>x</italic></sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>, where 1 &#x02264; <italic>x</italic> &#x0003C; <italic>y</italic> &#x02264; <italic>n</italic>.</p></list-item>
</list>
<p>If <italic>t</italic><sub><italic>x</italic></sub> &#x02192;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>, then we denote it as <italic>t</italic><sub><italic>x</italic></sub><italic>t</italic><sub><italic>y</italic></sub>. If <italic>t</italic><sub><italic>x</italic></sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>, then we denote it as {(<italic>t</italic><sub><italic>x</italic></sub>)(<italic>t</italic><sub><italic>y</italic></sub>)}. If <italic>t</italic><sub><italic>x</italic></sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>y</italic></sub>, <italic>t</italic><sub><italic>x</italic></sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>r</italic></sub>, and <italic>t</italic><sub><italic>y</italic></sub> &#x02192;<sub><italic>cd</italic></sub> <italic>t</italic><sub><italic>r</italic></sub>, then we denote it as {(<italic>t</italic><sub><italic>x</italic></sub>)(<italic>t</italic><sub><italic>y</italic></sub><italic>t</italic><sub><italic>r</italic></sub>)}. As shown in <xref ref-type="fig" rid="F1">Figure 1A</xref>, <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub>{(<italic>t</italic><sub>4</sub>)(<italic>t</italic><sub>7</sub>)}<italic>t</italic><sub>8</sub> is a firing sequence.</p>
<p><bold>Definition 12</bold> (Trace). Given a WFD-net system (<italic>ND, M</italic><sub>0</sub>) &#x0003D; (<italic>P, T, F, M</italic><sub>0</sub>, <italic>D, Guard, R, W, De, Gd</italic>), a trace in (<italic>ND, M</italic><sub>0</sub>) is a firing sequence &#x003C3;<sub><italic>i</italic></sub> &#x0003D; <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub> &#x022EF; <italic>t</italic><sub><italic>n</italic></sub>(<italic>n</italic> &#x02208; &#x02115;). The set of all traces is defined as <inline-formula><mml:math id="M15"><mml:mi>&#x003C6;</mml:mi><mml:mo>=</mml:mo><mml:msubsup><mml:mrow><mml:mo>&#x0222A;</mml:mo></mml:mrow><mml:mrow><mml:mi>i</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mi>k</mml:mi></mml:mrow></mml:msubsup><mml:mrow><mml:mo>{</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mi>i</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo>}</mml:mo></mml:mrow></mml:math></inline-formula>, where <italic>k</italic> is the number of traces.</p>
<p>The definition of a trace depends on the firing sequence, and there is no circulation relation by default. For the example of <xref ref-type="fig" rid="F1">Figure 1A</xref>, the traces are <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub>{(<italic>t</italic><sub>3</sub>)(<italic>t</italic><sub>5</sub><italic>t</italic><sub>6</sub>)}<italic>t</italic><sub>8</sub> and <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub>{(<italic>t</italic><sub>4</sub>)(<italic>t</italic><sub>7</sub>)}<italic>t</italic><sub>8</sub>. After then, we provide a way to compute the trace consistency degree of two WFD-net systems.</p></sec>
<sec>
<title>3.3. Trace consistency measurement method</title>
<p>Before providing the trace consistency measurement method, we must introduce <italic>correspondence relation</italic> and <italic>projected firing sequence</italic> in WFD-net systems. The correspondence relation of two WFD-net systems relates their transitions to each other. In the following, we formalize the correspondence relation.</p>
<p><bold>Definition 13</bold> [Correspondence relation (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>)]. Let (<italic>ND</italic><sub>1</sub>, <italic>M</italic><sub>01</sub>) &#x0003D; (<italic>P</italic><sub>1</sub>, <italic>T</italic><sub>1</sub>, <italic>F</italic><sub>1</sub>, <italic>M</italic><sub>01</sub>, <italic>D</italic><sub>1</sub>, <italic>Guard</italic><sub>1</sub>, <italic>R</italic><sub>1</sub>, <italic>W</italic><sub>1</sub>, <italic>De</italic><sub>1</sub>, <italic>Gd</italic><sub>1</sub>) and (<italic>ND</italic><sub>2</sub>, <italic>M</italic><sub>02</sub>) &#x0003D; (<italic>P</italic><sub>2</sub>, <italic>T</italic><sub>2</sub>, <italic>F</italic><sub>2</sub>, <italic>M</italic><sub>02</sub>, <italic>D</italic><sub>2</sub>, <italic>Guard</italic><sub>2</sub>, <italic>R</italic><sub>2</sub>, <italic>W</italic><sub>2</sub>, <italic>De</italic><sub>2</sub>, <italic>Gd</italic><sub>2</sub>) be two WFD-net systems. The non-empty correspondence relation &#x0007E;&#x02286; <italic>T</italic><sub>1</sub> &#x000D7; <italic>T</italic><sub>2</sub> aligns (<italic>ND</italic><sub>1</sub>, <italic>M</italic><sub>01</sub>) and (<italic>ND</italic><sub>2</sub>, <italic>M</italic><sub>02</sub>) by relating corresponding transitions to each other. <inline-formula><mml:math id="M16"><mml:msubsup><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x02286;</mml:mo><mml:msub><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow></mml:msub></mml:math></inline-formula> is a set of transitions with correspondences in (<italic>ND</italic><sub>1</sub>, <italic>M</italic><sub>01</sub>) satisfying <inline-formula><mml:math id="M17"><mml:msubsup><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:mrow><mml:mo>{</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mo>&#x02208;</mml:mo><mml:msub><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow></mml:msub><mml:mo>|</mml:mo><mml:mo>&#x02203;</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub><mml:mo>&#x02208;</mml:mo><mml:msub><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>:</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mo>&#x0007E;</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:mi>R</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>=</mml:mo><mml:mi>R</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>,</mml:mo><mml:mi>W</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>=</mml:mo><mml:mi>W</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>,</mml:mo><mml:mi>D</mml:mi><mml:mi>e</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>=</mml:mo><mml:mi>D</mml:mi><mml:mi>e</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>,</mml:mo><mml:mi>G</mml:mi><mml:mi>d</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:mo>=</mml:mo><mml:mi>G</mml:mi><mml:mi>d</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:mrow><mml:mo>}</mml:mo></mml:mrow></mml:math></inline-formula>. The set <inline-formula><mml:math id="M18"><mml:msubsup><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> for (<italic>ND</italic><sub>2</sub>, <italic>M</italic><sub>02</sub>) is defined analogously.</p>
<p>For the examples of <xref ref-type="fig" rid="F1">Figures 1A</xref>, <xref ref-type="fig" rid="F1">B</xref>, the set of transitions with correspondences in <xref ref-type="fig" rid="F1">Figure 1A</xref> is <inline-formula><mml:math id="M19"><mml:msubsup><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:mrow><mml:mo>{</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>5</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msub><mml:mo>,</mml:mo><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mn>8</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mo>}</mml:mo></mml:mrow></mml:math></inline-formula>.</p>
<p><bold>Definition 14</bold> [Projected firing sequence (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>)]. Let (<italic>ND</italic><sub>1</sub>, <italic>M</italic><sub>01</sub>) &#x0003D; (<italic>P</italic><sub>1</sub>, <italic>T</italic><sub>1</sub>, <italic>F</italic><sub>1</sub>, <italic>M</italic><sub>01</sub>, <italic>D</italic><sub>1</sub>, <italic>Guard</italic><sub>1</sub>, <italic>R</italic><sub>1</sub>, <italic>W</italic><sub>1</sub>, <italic>De</italic><sub>1</sub>, <italic>Gd</italic><sub>1</sub>) and (<italic>ND</italic><sub>2</sub>, <italic>M</italic><sub>02</sub>) &#x0003D; (<italic>P</italic><sub>2</sub>, <italic>T</italic><sub>2</sub>, <italic>F</italic><sub>2</sub>, <italic>M</italic><sub>02</sub>, <italic>D</italic><sub>2</sub>, <italic>Guard</italic><sub>2</sub>, <italic>R</italic><sub>2</sub>, <italic>W</italic><sub>2</sub>, <italic>De</italic><sub>2</sub>, <italic>Gd</italic><sub>2</sub>) be two WFD-net systems. The projected firing sequence &#x003C3;<sup>&#x0007E;</sup> is a firing sequence that contains all transitions with correspondences.</p>
<p>As shown in <xref ref-type="fig" rid="F1">Figure 1B</xref>, <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub>{(<italic>t</italic><sub>3</sub>)(<italic>t</italic><sub>5</sub>)}<italic>t</italic><sub>6</sub><italic>t</italic><sub>8</sub> is a projected firing sequence.</p>
<p><bold>Definition 15</bold> (Trace consistency degree of WFD-net systems, TCDW). Let (<italic>ND</italic><sub>1</sub>, <italic>M</italic><sub>01</sub>) &#x0003D; (<italic>P</italic><sub>1</sub>, <italic>T</italic><sub>1</sub>, <italic>F</italic><sub>1</sub>, <italic>M</italic><sub>01</sub>, <italic>D</italic><sub>1</sub>, <italic>Guard</italic><sub>1</sub>, <italic>R</italic><sub>1</sub>, <italic>W</italic><sub>1</sub>, <italic>De</italic><sub>1</sub>, <italic>Gd</italic><sub>1</sub>) and (<italic>ND</italic><sub>2</sub>, <italic>M</italic><sub>02</sub>) &#x0003D; (<italic>P</italic><sub>2</sub>, <italic>T</italic><sub>2</sub>, <italic>F</italic><sub>2</sub>, <italic>M</italic><sub>02</sub>, <italic>D</italic><sub>2</sub>, <italic>Guard</italic><sub>2</sub>, <italic>R</italic><sub>2</sub>, <italic>W</italic><sub>2</sub>, <italic>De</italic><sub>2</sub>, <italic>Gd</italic><sub>2</sub>) be two WFD-net systems. They are aligned by &#x0007E;. Let <inline-formula><mml:math id="M20"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> and <inline-formula><mml:math id="M21"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> be the sets of all projected firing sequences, such that <inline-formula><mml:math id="M22"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x02208;</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> and <inline-formula><mml:math id="M23"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x02208;</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> be the sets of same projected firing sequences. The trace consistency degree is defined as <inline-formula><mml:math id="M24"><mml:mi>T</mml:mi><mml:mi>C</mml:mi><mml:mi>D</mml:mi><mml:msup><mml:mrow><mml:mi>W</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:mfrac><mml:mrow><mml:msubsup><mml:mrow><mml:mo>|</mml:mo><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>|</mml:mo><mml:mo>&#x0002B;</mml:mo><mml:msubsup><mml:mrow><mml:mo>|</mml:mo><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>|</mml:mo></mml:mrow><mml:mrow><mml:msubsup><mml:mrow><mml:mo>|</mml:mo><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>|</mml:mo><mml:mo>&#x0002B;</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:msubsup><mml:mrow><mml:mo>|</mml:mo><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>|</mml:mo></mml:mrow></mml:mfrac></mml:math></inline-formula>.</p></sec>
<sec>
<title>3.4. Trace consistency degree of WFD-net systems</title>
<p>Notice that there are only 1:1 correspondence relation in this paper. The transitions with correspondence relations read, write and delete the same data items. Therefore, we use the same transitions to denote them (e.g., transitions <italic>t</italic><sub>1</sub> &#x0007E; <italic>t</italic><sub>8</sub> in <xref ref-type="fig" rid="F1">Figures 1A</xref>, <xref ref-type="fig" rid="F1">B</xref>). A trace consistency guarantees that the essential rotes are reserved among transitions with correspondences in two WFD-net systems. According to our method, the inconsistencies manifest there exist traces without correspondence.</p>
<p>According to Def. 15, we propose <xref ref-type="table" rid="T4">Algorithm 1</xref> to calculate the trace consistency degree. This algorithm uses the sets of projected firing sequences <inline-formula><mml:math id="M25"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> and <inline-formula><mml:math id="M26"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>, and the sets of the same projected firing sequences <inline-formula><mml:math id="M27"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> and <inline-formula><mml:math id="M28"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> in two WFD-net systems as inputs, and the trace consistency degree <italic>TCDW</italic><sup>&#x0007E;</sup> as outputs. Step 1 initializes <italic>TCDW</italic><sup>&#x0007E;</sup>, <inline-formula><mml:math id="M29"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>, <inline-formula><mml:math id="M30"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>, <inline-formula><mml:math id="M31"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>, and <inline-formula><mml:math id="M32"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>. <inline-formula><mml:math id="M33"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> and <inline-formula><mml:math id="M34"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mtext>&#x000A0;</mml:mtext></mml:math></inline-formula>can be calculated by taking Steps 2&#x02013;7. <inline-formula><mml:math id="M35"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> and <inline-formula><mml:math id="M36"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> are derived from Steps 8&#x02013;21. Finally, the trace consistency degree <italic>TCDW</italic><sup>&#x0007E;</sup> is calculated according to <inline-formula><mml:math id="M37"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>, <inline-formula><mml:math id="M38"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>, <inline-formula><mml:math id="M39"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>, and <inline-formula><mml:math id="M40"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>, as shown in Step 22.</p>
<table-wrap position="float" id="T4">
<label>Algorithm 1</label>
<caption><p>Trace consistency degree of two WFD-net systems.</p></caption>
<table frame="box" rules="all">
<tbody>
<tr>
<td valign="top" align="left"><bold>Input: Two</bold> WFD-net systems (<italic>ND</italic><sub>1</sub>, <italic>M</italic><sub>01</sub>) and (<italic>ND</italic><sub>2</sub>, <italic>M</italic><sub>02</sub>) with the sets of projected firing sequences <inline-formula><mml:math id="M41"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> and <inline-formula><mml:math id="M42"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>, and the sets of same projected firing sequences <inline-formula><mml:math id="M43"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> and <inline-formula><mml:math id="M44"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>.</td>
</tr>
<tr>
<td valign="top" align="left"><bold>Output:</bold> Trace consistency degree of two WFD-net systems: <italic>TCDW</italic><sup>&#x0007E;</sup></td>
</tr>
<tr>
<td valign="top" align="left">1: <italic>TCDW</italic><sup>&#x0007E;</sup> &#x0003D; &#x02205;, <inline-formula><mml:math id="M45"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:mo class="MathClass-ord">&#x02205;</mml:mo></mml:math></inline-formula>, <inline-formula><mml:math id="M46"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:mo class="MathClass-ord">&#x02205;</mml:mo></mml:math></inline-formula>, <inline-formula><mml:math id="M47"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:mo class="MathClass-ord">&#x02205;</mml:mo></mml:math></inline-formula>, and <inline-formula><mml:math id="M48"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:mo class="MathClass-ord">&#x02205;</mml:mo></mml:math></inline-formula>;</td>
</tr>
<tr>
<td valign="top" align="left">2: <bold>for</bold> &#x003C6;<sub><italic>a</italic></sub> &#x02208; &#x003C6;<sub>1</sub> and &#x02203;<italic>t</italic><sub><italic>i</italic></sub> &#x02208; &#x003C6;<sub><italic>a</italic></sub>:<italic>t</italic><sub><italic>i</italic></sub> &#x02209; &#x003C6;<sub>2</sub> <bold>do</bold></td>
</tr>
<tr>
<td valign="top" align="left">3: <inline-formula><mml:math id="M49"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x0222A;</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mfrac><mml:mrow><mml:msub><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mi>a</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>i</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:mfrac></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math></inline-formula></td>
</tr>
<tr>
<td valign="top" align="left">4: <bold>end for</bold></td>
</tr>
<tr>
<td valign="top" align="left">5: <bold>for</bold> &#x003C6;<sub><italic>b</italic></sub> &#x02208; &#x003C6;<sub>2</sub> and &#x02203;<italic>t</italic><sub><italic>j</italic></sub> &#x02208; &#x003C6;<sub><italic>b</italic></sub>:<italic>t</italic><sub><italic>j</italic></sub> &#x02209; &#x003C6;<sub>1</sub> <bold>do</bold></td>
</tr>
<tr>
<td valign="top" align="left">6: <inline-formula><mml:math id="M50"><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x0222A;</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mrow><mml:mfrac><mml:mrow><mml:msub><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mi>b</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>t</mml:mi></mml:mrow><mml:mrow><mml:mi>j</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:mfrac></mml:mrow><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math></inline-formula></td>
</tr>
<tr>
<td valign="top" align="left">7: <bold>end for</bold></td>
</tr>
<tr>
<td valign="top" align="left">8: <bold>for</bold> <inline-formula><mml:math id="M51"><mml:mo>&#x02200;</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x02208;</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>, <inline-formula><mml:math id="M52"><mml:msubsup><mml:mrow><mml:mo>&#x02203;</mml:mo><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mi>d</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x02208;</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> <bold>do</bold></td>
</tr>
<tr>
<td valign="top" align="left">9: &#x000A0;&#x000A0;&#x000A0;&#x000A0;<bold>if</bold> <inline-formula><mml:math id="M53"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mi>d</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> <bold>then</bold></td>
</tr>
<tr>
<td valign="top" align="left">10: &#x000A0;&#x000A0;&#x000A0;&#x000A0;&#x000A0;&#x000A0;&#x000A0;&#x000A0;<inline-formula><mml:math id="M54"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x0222A;</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>;</td>
</tr>
<tr>
<td valign="top" align="left">11: &#x000A0;&#x000A0;&#x000A0;&#x000A0;<bold>else</bold></td>
</tr>
<tr>
<td valign="top" align="left">12: &#x000A0;&#x000A0;&#x000A0;&#x000A0;&#x000A0;&#x000A0;&#x000A0;&#x000A0;<inline-formula><mml:math id="M55"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>;</mml:mo></mml:math></inline-formula></td>
</tr>
<tr>
<td valign="top" align="left">13: &#x000A0;&#x000A0;&#x000A0;&#x000A0;<bold>end if</bold></td>
</tr>
<tr>
<td valign="top" align="left">14: <bold>end for</bold></td>
</tr>
<tr>
<td valign="top" align="left">15: <bold>for</bold> <inline-formula><mml:math id="M56"><mml:mo>&#x02200;</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x02208;</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>, <inline-formula><mml:math id="M57"><mml:msubsup><mml:mrow><mml:mo>&#x02203;</mml:mo><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mi>f</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x02208;</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> <bold>do</bold></td>
</tr>
<tr>
<td valign="top" align="left">16: <bold>if</bold> <inline-formula><mml:math id="M58"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mi>f</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> <bold>then</bold></td>
</tr>
<tr>
<td valign="top" align="left">17: <inline-formula><mml:math id="M59"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>&#x0222A;</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mi>f</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>;</td>
</tr>
<tr>
<td valign="top" align="left">18: <bold>else</bold></td>
</tr>
<tr>
<td valign="top" align="left">19: <inline-formula><mml:math id="M60"><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>=</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:msubsup><mml:mrow><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula>;</td>
</tr>
<tr>
<td valign="top" align="left">20: <bold>end if</bold></td>
</tr>
<tr>
<td valign="top" align="left">21: <bold>end for</bold></td>
</tr>
<tr>
<td valign="top" align="left">22: <inline-formula><mml:math id="M61"><mml:mi>T</mml:mi><mml:mi>C</mml:mi><mml:mi>D</mml:mi><mml:msup><mml:mrow><mml:mi>W</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:mfrac><mml:mrow><mml:msubsup><mml:mrow><mml:mo>|</mml:mo><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>|</mml:mo><mml:mo>&#x0002B;</mml:mo><mml:msubsup><mml:mrow><mml:mo>|</mml:mo><mml:mi>&#x003C3;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>|</mml:mo></mml:mrow><mml:mrow><mml:msubsup><mml:mrow><mml:mo>|</mml:mo><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>|</mml:mo><mml:mo>&#x0002B;</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:msubsup><mml:mrow><mml:mo>|</mml:mo><mml:mi>&#x003C6;</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msubsup><mml:mo>|</mml:mo></mml:mrow></mml:mfrac></mml:math></inline-formula>;</td>
</tr>
</tbody>
</table>
</table-wrap>
<p>The number of firing sequences in (<italic>ND</italic><sub>1</sub>, <italic>M</italic><sub>01</sub>) is <italic>n</italic><sub>1</sub>, and the number of firing sequences in (<italic>ND</italic><sub>2</sub>, <italic>M</italic><sub>02</sub>) is <italic>n</italic><sub>2</sub>. The time cost of finding projected firing sequences in (<italic>ND</italic><sub>1</sub>, <italic>M</italic><sub>01</sub>) and (<italic>ND</italic><sub>2</sub>, <italic>M</italic><sub>02</sub>) is <italic>n</italic><sub>1</sub> &#x0002B; <italic>n</italic><sub>2</sub>. Let <italic>n</italic> be the number of the max firing sequences in these two models [i.e., <italic>n</italic> &#x0003D; <italic>max</italic>(<italic>n</italic><sub>1</sub>, <italic>n</italic><sub>2</sub>)], and then their projected firing sequences can be found in <italic>O</italic>(<italic>n</italic><sup>2</sup>). The calculation of trace consistency degree is in linear time with the calculation of projected firing sequences. Therefore, the time complexity of this algorithm is <italic>O</italic>(<italic>n</italic><sup>2</sup>).</p>
<p>According to the DTC method, there are 10 traces in <xref ref-type="fig" rid="F1">Figures 1A</xref>, <xref ref-type="fig" rid="F1">B</xref> if data operations and guard functions are ignored. The traces in <xref ref-type="fig" rid="F1">Figures 1A</xref>, <xref ref-type="fig" rid="F1">B</xref> are <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub>{(<italic>t</italic><sub>3</sub>)(<italic>t</italic><sub>5</sub><italic>t</italic><sub>6</sub>)}<italic>t</italic><sub>8</sub>, <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub>{(<italic>t</italic><sub>4</sub>)(<italic>t</italic><sub>5</sub><italic>t</italic><sub>6</sub>)}<italic>t</italic><sub>8</sub>, <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub>{(<italic>t</italic><sub>3</sub>)(<italic>t</italic><sub>7</sub>)}<italic>t</italic><sub>8</sub>, and <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub>{(<italic>t</italic><sub>4</sub>)(<italic>t</italic><sub>7</sub>)}<italic>t</italic><sub>8</sub>, as shown in <xref ref-type="fig" rid="F4">Figure 4A</xref>. Therefore, the trace consistency degree of these two models computed by the DTC method is 1.</p>
<fig id="F4" position="float">
<label>Figure 4</label>
<caption><p>DTC (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>) method: <bold>(A)</bold> shows the traces of <xref ref-type="fig" rid="F1">Figures 1A</xref>, <xref ref-type="fig" rid="F1">B</xref>. Our method: <bold>(B)</bold> reveals the traces of <xref ref-type="fig" rid="F1">Figure 1A</xref>, <bold>(C)</bold> illustrates the traces of <xref ref-type="fig" rid="F1">Figure 1B</xref>.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fcomp-05-1136057-g0004.tif"/>
</fig>
<p>However, there are 5 traces (resp. 4 traces) in <xref ref-type="fig" rid="F1">Figure 1A</xref> (resp. <xref ref-type="fig" rid="F1">Figure 1A</xref>) when data operations and guard functions are considered. The traces in <xref ref-type="fig" rid="F1">Figure 1A</xref> are <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub>{(<italic>t</italic><sub>3</sub>)(<italic>t</italic><sub>5</sub><italic>t</italic><sub>6</sub>)}<italic>t</italic><sub>8</sub>, <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub>{(<italic>t</italic><sub>4</sub>)(<italic>t</italic><sub>7</sub>)}<italic>t</italic><sub>8</sub>, and the traces in <xref ref-type="fig" rid="F1">Figure 1B</xref> are <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub>{(<italic>t</italic><sub>3</sub>)(<italic>t</italic><sub>5</sub>)}<italic>t</italic><sub>6</sub><italic>t</italic><sub>8</sub> and <italic>t</italic><sub>1</sub><italic>t</italic><sub>2</sub>{(<italic>t</italic><sub>4</sub>)(<italic>t</italic><sub>7</sub>)}<italic>t</italic><sub>8</sub>, as shown in <xref ref-type="fig" rid="F4">Figures 4B</xref>, <xref ref-type="fig" rid="F4">C</xref>. Therefore, the trace consistency degree of these two models is <inline-formula><mml:math id="M62"><mml:mi>T</mml:mi><mml:mi>C</mml:mi><mml:mi>D</mml:mi><mml:msup><mml:mrow><mml:mi>W</mml:mi></mml:mrow><mml:mrow><mml:mo>&#x0007E;</mml:mo></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:mfrac><mml:mrow><mml:mn>4</mml:mn><mml:mo>&#x0002B;</mml:mo><mml:mn>4</mml:mn></mml:mrow><mml:mrow><mml:mn>5</mml:mn><mml:mo>&#x0002B;</mml:mo><mml:mn>4</mml:mn></mml:mrow></mml:mfrac><mml:mo>&#x02248;</mml:mo><mml:mtext>&#x000A0;</mml:mtext><mml:mn>0</mml:mn><mml:mo>.</mml:mo><mml:mn>889</mml:mn></mml:math></inline-formula>.</p></sec></sec>
<sec id="s4">
<title>4. Experiments</title>
<p>To evaluate the trace consistency of eight pieces of pseudo-code (i.e., <xref ref-type="table" rid="T2">Tables 2</xref>, <xref ref-type="table" rid="T3">3</xref>), we use eight WFD-net systems to model them, as shown in <xref ref-type="fig" rid="F5">Figures 5</xref>, <bold>8</bold>. Although the method of DTC (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>) can be used to measure the trace consistency degree, we want to address the following three problems.</p>
<list list-type="simple">
<list-item><p>RQ1: How do guard functions affect the traces in WFD-net systems?</p></list-item>
<list-item><p>RQ2: How do data dependencies affect the traces in WFD-net systems?</p></list-item>
<list-item><p>RQ3: Is our method more effective in measuring the trace consistency degree?</p></list-item>
</list>
<table-wrap position="float" id="T2">
<label>Table 2</label>
<caption><p>Four kinds of pseudo-codes with guard functions.</p></caption>
<table frame="box" rules="all">
<thead>
<tr style="background-color:#919498;color:#ffffff">
<th valign="top" align="left"><bold>1</bold></th>
<th valign="top" align="left"><bold>2</bold></th>
<th valign="top" align="left"><bold>3</bold></th>
<th valign="top" align="left"><bold>4</bold></th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">{<italic>t</italic><sub>1</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>1</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>1</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>1</sub>}</td>
</tr> <tr>
<td valign="top" align="left">Thread1()</td>
<td valign="top" align="left">If (<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>))</td>
<td valign="top" align="left">If (<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>))</td>
<td valign="top" align="left">If (<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>))</td>
</tr> <tr>
<td valign="top" align="left">If (<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>))</td>
<td valign="top" align="left">Thread1()</td>
<td valign="top" align="left">Thread1()</td>
<td valign="top" align="left">Thread1()</td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub>2</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>2</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>2</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>2</sub>}</td>
</tr> <tr>
<td valign="top" align="left">Else</td>
<td valign="top" align="left">Thread2()</td>
<td valign="top" align="left">Thread2()</td>
<td valign="top" align="left">Thread2()</td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub>3</sub>} If (<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>))</td>
<td valign="top" align="left">{<italic>t</italic><sub>3</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>4</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>5</sub>}</td>
</tr> <tr>
<td valign="top" align="left">End if</td>
<td valign="top" align="left">Else</td>
<td valign="top" align="left">Else</td>
<td valign="top" align="left">Else</td>
</tr> <tr>
<td valign="top" align="left">Thread2()</td>
<td valign="top" align="left">Thread3()</td>
<td valign="top" align="left">Thread3()</td>
<td valign="top" align="left">Thread3()</td>
</tr> <tr>
<td valign="top" align="left">If (<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>))</td>
<td valign="top" align="left">{<italic>t</italic><sub>4</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>3</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>3</sub>}</td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub>4</sub>}</td>
<td valign="top" align="left">Thread4()</td>
<td valign="top" align="left">Thread4()</td>
<td valign="top" align="left">Thread4()</td>
</tr> <tr>
<td valign="top" align="left">Else</td>
<td valign="top" align="left">{<italic>t</italic><sub>5</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>5</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>4</sub>}</td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub>5</sub>}</td>
<td valign="top" align="left">End if</td>
<td valign="top" align="left">End if</td>
<td valign="top" align="left">End if</td>
</tr> <tr>
<td valign="top" align="left">End if</td>
<td valign="top" align="left">{<italic>t</italic><sub>6</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>6</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>6</sub>}</td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub>6</sub>}</td>
<td/>
<td/>
<td/>
</tr></tbody>
</table>
</table-wrap>
<table-wrap position="float" id="T3">
<label>Table 3</label>
<caption><p>Four kinds of pseudo-codes with data dependencies.</p></caption>
<table frame="box" rules="all">
<thead>
<tr style="background-color:#919498;color:#ffffff">
<th valign="top" align="left"><bold>1</bold></th>
<th valign="top" align="left"><bold>2</bold></th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">{<italic>t</italic><sub>1</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>1</sub>}</td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub>2</sub>}:<italic>int</italic> &#x0002A; <italic>d</italic> &#x0003D; <italic>new int</italic>, &#x0002A; <italic>d</italic> &#x0003D; 3</td>
<td valign="top" align="left">Thread1()</td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub>3</sub>}:<italic>c</italic> &#x0003D; <italic>d, delete</italic>(<italic>d</italic>), <italic>d</italic> &#x0003D; <italic>NULL</italic></td>
<td valign="top" align="left">{<italic>t</italic><sub>2</sub>}:<italic>int</italic> &#x0002A; <italic>d</italic> &#x0003D; <italic>new int</italic>, &#x0002A; <italic>d</italic> &#x0003D; 3</td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub>4</sub>}</td>
<td valign="top" align="left">Thread2()</td>
</tr> <tr>
<td/>
<td valign="top" align="left">{<italic>t</italic><sub>3</sub>}:<italic>c</italic> &#x0003D; <italic>d, delete</italic>(<italic>d</italic>), <italic>d</italic> &#x0003D; <italic>NULL</italic></td>
</tr> <tr>
<td/>
<td valign="top" align="left">{<italic>t</italic><sub>4</sub>}</td>
</tr> <tr style="background-color:#919498;color:#ffffff">
<td valign="top" align="left"><bold>3</bold></td>
<td valign="top" align="left"><bold>4</bold></td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub><italic>x</italic></sub>}:<italic>int</italic> &#x0002A; <italic>d</italic> &#x0003D; <italic>new int</italic>, &#x0002A; <italic>d</italic> &#x0003D; 3</td>
<td valign="top" align="left">{<italic>t</italic><sub><italic>y</italic></sub>}:<italic>int</italic> &#x0002A; <italic>d</italic> &#x0003D; <italic>new int</italic>, &#x0002A; <italic>d</italic> &#x0003D; 3</td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub>1</sub>}</td>
<td valign="top" align="left">{<italic>t</italic><sub>1</sub>}</td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub>2</sub>}:<italic>int</italic> &#x0002A; <italic>d</italic> &#x0003D; <italic>new int</italic>, &#x0002A; <italic>d</italic> &#x0003D; 3</td>
<td valign="top" align="left">Thread1()</td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub>3</sub>}:<italic>c</italic> &#x0003D; <italic>d, delete</italic>(<italic>d</italic>), <italic>d</italic> &#x0003D; <italic>NULL</italic></td>
<td valign="top" align="left">{<italic>t</italic><sub>2</sub>}:<italic>int</italic> &#x0002A; <italic>d</italic> &#x0003D; <italic>new int</italic>, &#x0002A; <italic>d</italic> &#x0003D; 3</td>
</tr> <tr>
<td valign="top" align="left">{<italic>t</italic><sub>4</sub>}</td>
<td valign="top" align="left">Thread2()</td>
</tr> <tr>
<td/>
<td valign="top" align="left">{<italic>t</italic><sub>3</sub>}:<italic>c</italic> &#x0003D; <italic>d, delete</italic>(<italic>d</italic>), <italic>d</italic> &#x0003D; <italic>NULL</italic></td>
</tr> <tr>
<td/>
<td valign="top" align="left">{<italic>t</italic><sub>4</sub>}</td>
</tr></tbody>
</table>
</table-wrap>
<fig id="F5" position="float">
<label>Figure 5</label>
<caption><p><bold>(A&#x02013;D)</bold> are WFD-net models of <xref ref-type="table" rid="T2">Table 2</xref>.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fcomp-05-1136057-g0005.tif"/>
</fig>
<p>To answer RQ1-RQ3, we analyze the above-mentioned eight WFD-net systems. These systems include weak strict order relations, weak exclusiveness relations, and weak interleaving order relations. To compare our method with the DTC method, we analyze the trace consistency degree of these models with guard functions and data dependencies.</p>
<sec>
<title>4.1. RQ1: The effect of guard functions on traces</title>
<p>As shown in Section 3, we know the guard functions may change the behavioral relations. Therefore, we discuss the traces in the general cases (e.g., <xref ref-type="fig" rid="F5">Figure 5A</xref>) as follows:</p>
<list list-type="order">
<list-item><p>If there exists no data item <italic>d</italic> satisfying <italic>d</italic> &#x02208; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>)) &#x02229; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)), we have (<italic>t</italic><sub>2</sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>2</sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) in <xref ref-type="fig" rid="F5">Figure 5A</xref>. The corresponding traces are illustrated in <xref ref-type="fig" rid="F6">Figure 6A</xref>.</p></list-item>
<list-item><p>If &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>))) &#x0003D; &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>))), then we have (<italic>t</italic><sub>2</sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>2</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) in <xref ref-type="fig" rid="F5">Figure 5A</xref>. The corresponding traces are illustrated in <xref ref-type="fig" rid="F6">Figure 6B</xref>.</p></list-item>
<list-item><p>If &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>))) &#x0003D; &#x00393;(<italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>))), then we have (<italic>t</italic><sub>2</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>2</sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) in <xref ref-type="fig" rid="F5">Figure 5A</xref>. The corresponding traces are illustrated in <xref ref-type="fig" rid="F6">Figure 6C</xref>.</p></list-item>
<list-item><p>If <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>)) &#x02229; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)) &#x0003D; {&#x1D507;} and &#x02200;<italic>d</italic> &#x02208; &#x1D507;:[<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>))) &#x02229; &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>)))) &#x02260; &#x02205;] &#x02227; [<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>))) &#x02229; &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>)))) &#x02260; &#x02205;], we have (<italic>t</italic><sub>2</sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>2</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) in <xref ref-type="fig" rid="F5">Figure 5A</xref>. The corresponding traces are illustrated in <xref ref-type="fig" rid="F6">Figure 6D</xref>.</p></list-item>
<list-item><p>If <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>)) &#x02229; <italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)) &#x0003D; {&#x1D507;}, and &#x02200;<italic>d</italic> &#x02208; &#x1D507;:[<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>))) &#x02229; &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>)))) &#x02260; &#x02205;] &#x02227; [<italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>))) &#x02229; &#x00393;(<italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>)))) &#x02260; &#x02205;], we have (<italic>t</italic><sub>2</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>2</sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) in <xref ref-type="fig" rid="F5">Figure 5A</xref>. The corresponding traces are illustrated in <xref ref-type="fig" rid="F6">Figure 6E</xref>.</p></list-item>
<list-item><p>If <italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>)) &#x02229; <italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)) &#x0003D; {&#x1D507;}, and &#x02200;<italic>d</italic> &#x02208; &#x1D507;:[<italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>))) &#x02229; &#x00393;(<italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>)))) &#x02260; &#x02205;] &#x02227; [<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>))) &#x02229; &#x00393;(<italic>Rel</italic>(<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>)))) &#x02260; &#x02205;], we have (<italic>t</italic><sub>2</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>2</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) in <xref ref-type="fig" rid="F5">Figure 5A</xref>. The corresponding traces are illustrated in <xref ref-type="fig" rid="F6">Figure 6F</xref>.</p></list-item>
<list-item><p>If <italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>)) &#x02229; <italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>)) &#x0003D; {&#x1D507;}, and &#x02200;<italic>d</italic> &#x02208; &#x1D507;:[<italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>))) &#x02229; &#x00393;(<italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>x</italic></sub>(<italic>d</italic>)))) &#x02260; &#x02205;] &#x02227; [<italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>))) &#x02229; &#x00393;(<italic>Rel</italic>(&#x000AC;<italic>Gd</italic>(<italic>t</italic><sub><italic>y</italic></sub>(<italic>d</italic>)))) &#x02260; &#x02205;], we have (<italic>t</italic><sub>2</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>2</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x0002B;<sub><italic>cd</italic></sub> <italic>t</italic><sub>4</sub>) &#x02227; (<italic>t</italic><sub>3</sub> &#x02225;<sub><italic>cd</italic></sub> <italic>t</italic><sub>5</sub>) in <xref ref-type="fig" rid="F5">Figure 5A</xref>. The corresponding traces are illustrated in <xref ref-type="fig" rid="F6">Figure 6G</xref>.</p></list-item>
</list>
<fig id="F6" position="float">
<label>Figure 6</label>
<caption><p>DTC (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>) method: <bold>(A)</bold> shows the traces of <xref ref-type="fig" rid="F5">Figure 5A</xref>, <bold>(H)</bold> shows the traces of <xref ref-type="fig" rid="F5">Figure 5B</xref>, <bold>(B)</bold> shows the traces of <xref ref-type="fig" rid="F5">Figure 5C</xref>, and <bold>(C)</bold> shows the traces of <xref ref-type="fig" rid="F5">Figure 5D</xref>. Our method: <bold>(A&#x02013;G)</bold> shows the traces of <xref ref-type="fig" rid="F5">Figure 5A</xref>, <bold>(H)</bold> shows the traces of <xref ref-type="fig" rid="F5">Figure 5B</xref>, <bold>(B)</bold> shows the traces of <xref ref-type="fig" rid="F5">Figure 5C</xref>, and <bold>(C)</bold> shows the traces of <xref ref-type="fig" rid="F5">Figure 5D</xref>.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fcomp-05-1136057-g0006.tif"/>
</fig>
<p>In our method, <xref ref-type="fig" rid="F6">Figure 6H</xref> shows the traces of <xref ref-type="fig" rid="F5">Figure 5B</xref>, <xref ref-type="fig" rid="F6">Figure 6B</xref> shows the traces of <xref ref-type="fig" rid="F5">Figure 5C</xref>, and <xref ref-type="fig" rid="F6">Figure 6C</xref> shows the traces of <xref ref-type="fig" rid="F5">Figure 5D</xref>. Therefore, the traces in a WFD-net system are more than one when their guard functions are uncertain, e.g., <xref ref-type="fig" rid="F5">Figure 5A</xref>. <xref ref-type="fig" rid="F7">Figure 7</xref> shows the trace consistency degrees of models in <xref ref-type="fig" rid="F5">Figures 5A&#x02013;D</xref>.</p>
<fig id="F7" position="float">
<label>Figure 7</label>
<caption><p>Trace consistency degree measurement results by taking DTC (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>) and TCDW methods.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fcomp-05-1136057-g0007.tif"/>
</fig></sec>
<sec>
<title>4.2. RQ2: The effect of data dependencies on traces</title>
<p>In this subsection, we discuss the traces that may be affected by data dependencies, as shown in <xref ref-type="fig" rid="F8">Figure 8</xref>. Based on Def. 7, the data dependencies in <xref ref-type="fig" rid="F8">Figures 8A</xref>, <xref ref-type="fig" rid="F8">C</xref>, <xref ref-type="fig" rid="F8">D</xref> cannot change the traces. Although we have <italic>d</italic> &#x022D6; <italic>MD</italic> in <xref ref-type="fig" rid="F8">Figure 8B</xref>, the final place can be reached. The data dependencies in <xref ref-type="fig" rid="F8">Figure 8B</xref> can change the traces if there is no locking mechanism. In a word, we have <italic>t</italic><sub>2</sub> &#x02192;<sub><italic>cd</italic></sub> <italic>t</italic><sub>3</sub> in <xref ref-type="fig" rid="F8">Figure 8B</xref>. Therefore, the corresponding traces of <xref ref-type="fig" rid="F8">Figures 8A&#x02013;D</xref> are shown in <xref ref-type="fig" rid="F9">Figure 9</xref>. <xref ref-type="fig" rid="F10">Figure 10</xref> shows the trace consistency degrees of models in <xref ref-type="fig" rid="F8">Figures 8A&#x02013;D</xref>.</p>
<fig id="F8" position="float">
<label>Figure 8</label>
<caption><p><bold>(A&#x02013;D)</bold> are WFD-net models of <xref ref-type="table" rid="T3">Table 3</xref>.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fcomp-05-1136057-g0008.tif"/>
</fig>
<fig id="F9" position="float">
<label>Figure 9</label>
<caption><p>DTC (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>) method: <bold>(A)</bold> reveals the traces of <xref ref-type="fig" rid="F8">Figures 8A</xref>, <xref ref-type="fig" rid="F8">C</xref>, <bold>(B)</bold> shows the traces of <xref ref-type="fig" rid="F8">Figures 8B</xref>, <xref ref-type="fig" rid="F8">D</xref>. Our method: <bold>(A)</bold> illustrates the traces of <xref ref-type="fig" rid="F8">Figures 8A&#x02013;C</xref>, <bold>(B)</bold> shows the traces of <xref ref-type="fig" rid="F8">Figure 8D</xref>.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fcomp-05-1136057-g0009.tif"/>
</fig>
<fig id="F10" position="float">
<label>Figure 10</label>
<caption><p>Trace consistency degree measurement results by taking DTC (Weidlich et al., <xref ref-type="bibr" rid="B34">2011</xref>) and TCDW methods.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fcomp-05-1136057-g0010.tif"/>
</fig></sec>
<sec>
<title>4.3. RQ3: Comparison between different trace consistency measurement methods</title>
<p>In this subsection, we present a comparison between different methods for trace consistency measurements. The comparison includes two methods in total. The DTC method does not consider the trace consistency degree affected by guard functions and data dependencies of transitions. The results of our method (i.e., TCDW) take both sides into consideration, especially when the values of guard functions are uncertain.</p>
<p>In <xref ref-type="fig" rid="F7">Figure 7</xref>, we can get 3 kinds of trace consistency degrees of <xref ref-type="fig" rid="F5">Figures 5A</xref>, <xref ref-type="fig" rid="F5">C</xref> as the values of guard functions are uncertain, i.e., <italic>TCDW</italic><sub>1</sub> &#x0003D; 0, 0.667 or 1. <xref ref-type="fig" rid="F7">Figures 7</xref>, <xref ref-type="fig" rid="F10">10</xref> present the comparison results of the DTC method with the TCDW method on trace consistency measurement. Obviously, our result is more reasonable than the existing methods.</p></sec></sec>
<sec id="s5">
<title>5. Related work</title>
<p>Consistency checking has become a critical technology in checking how a process model is similar to another. It is significant in the matching process models (Weidlich et al., <xref ref-type="bibr" rid="B31">2012</xref>). Existing studies on the measurements of consistency degree can be classified into two categories: with or without data. The following parts review some related work about the existing measuring methods.</p>
<sec>
<title>5.1. Consistency degree of process models without data</title>
<p>Consistency measurement is very important in process alignment and process integration. It can be taken to detect the deviations between the process models and corresponding event logs. Recently, many researchers have focused on measuring the consistency degrees of process models from the angle of control flow.</p>
<p>Decker and Weske (<xref ref-type="bibr" rid="B3">2007</xref>) presented the standard for an optimum consistency relation regarding a given compatibility relation. They guaranteed that the implemented services&#x00027; behaviors were compatible with others. Therefore, they checked the consistency degree of specifications and service implementations. After then, van der Aalst (<xref ref-type="bibr" rid="B27">2011</xref>) and van der Aalst et al. (<xref ref-type="bibr" rid="B29">2007</xref>) depicted the conformity relationship between event logs and process models. The consistency measurement techniques can be used to compare the modeled behavior in the initial process model with the observed behavior in event logs. The consistency guarantees there is no contradiction between the two models (Rull et al., <xref ref-type="bibr" rid="B18">2008</xref>). Rozinat and van der Aalst (<xref ref-type="bibr" rid="B17">2008</xref>) proposed a method to check the consistency of an event log to a process model. This method is based on monitoring real behavior. Unfortunately, these studies cannot distinguish between slight inconsistencies and complete inconsistencies.</p>
<p>Based on existing research, Weidlich and Mendling (<xref ref-type="bibr" rid="B33">2010</xref>), Weidlich and van der Werf (<xref ref-type="bibr" rid="B35">2012</xref>), and Weidlich et al. (<xref ref-type="bibr" rid="B34">2011</xref>) solved this problem. They defined behavioral profile relations that can capture the behavioral restrictions of a model. Moreover, they put forward the trace consistency as the number of the same traces in two models to the number of traces with transitions in correspondences. Additionally, based on correspondence relations, they defined the profile consistency degree. They also illustrated that consistency-checking technology states how the real behavior is consistent with the observed. After then, Nagel et al. (<xref ref-type="bibr" rid="B16">2013</xref>) described process model quality constraints that can be taken to obtain consistency among the goals and the process models. van der Aa et al. (<xref ref-type="bibr" rid="B26">2015</xref>) used natural language processing techniques to recognize the inconsistencies between textual descriptions and relevant process models. Awadid and Nurcan (<xref ref-type="bibr" rid="B2">2016</xref>) reviewed the existing consistency measurement methods. One aim of their research is to master the inter-model consistency issue. Besides, Wang et al. (<xref ref-type="bibr" rid="B30">2018</xref>) proposed relation profile methods to analyze the consistency degrees of different process models. Although these consistency measurement methods have been proposed, they mostly rely on detecting the consistency decrease caused by the difference in process models. They have not taken the data dependencies or guard functions into consideration.</p></sec>
<sec>
<title>5.2. Consistency degree of process models with data</title>
<p>Generally speaking, the consistency degree of process models in workflow systems would be affected by the data. Song et al. (<xref ref-type="bibr" rid="B24">2013</xref>) and Song and Jacobsen (<xref ref-type="bibr" rid="B20">2015</xref>) proposed a way to calculate the consistency degrees between conceptual and executable process models. At the same time, they developed a tool named COCO to quantitatively calculate the consistency degree. After then, they measured the trace consistency degree between the two models on account of control dependence and data dependence and provided a new computing method to quantify the trace consistency (Song et al., <xref ref-type="bibr" rid="B23">2021</xref>). Based on the program dependency graphs, Zhang et al. (<xref ref-type="bibr" rid="B38">2018</xref>) and Zhang et al. (<xref ref-type="bibr" rid="B37">2019</xref>) proposed a systematic method to check consistencies between different BPEL processes. They identified that the data dependencies can affect the consistency degrees of different models. They took advantage of activity constraint graphs to calculate the consistency degree of models with control flow and data-flow information. After taking their methods, we can distinguish different event constraints and check the consistency of conceptual and logical process models.</p>
<p>However, these studies are mainly based on analyzing the consistency of physical processes with read/write operations. They have not considered that the guard functions may affect the trace consistency degree. Usually, the transitions without correspondence relations but with data dependencies are ignored by them, too. However, all of them may affect the real trace consistency degree. By comparison, our measurement methods can solve these problems.</p></sec></sec>
<sec id="s6">
<title>6. Conclusions and future work</title>
<p>The trace consistency measurement is important to service-based workflow net systems. This paper presents the behavioral profile relation in a WFD-net system, and provides a new way to calculate the trace consistency of two WFD-net systems. Compared with the DTC method, the advantages of our method are shown as follows. Firstly, we illustrate that the guard functions may affect the traces in two WFD-net systems. Therefore, the trace consistency degree is non-uniqueness when the values of guard functions are uncertain. Secondly, we point out that the transitions with or without correspondence but with some data dependencies can also affect the traces and the real trace consistency degree. Some experiments on WFD-net systems above demonstrate that our method is more efficient in measuring trace consistency than the existing method.</p>
<p>This paper shows some directions for future research:
<list list-type="order">
<list-item><p>Our methods need to be improved so as to measure the trace consistency between transitions in WFD-net systems extended with complex correspondence relations;</p></list-item>
<list-item><p>Some measures should be taken to repair control/data-flow errors as they may affect the actual traces; and</p></list-item>
<list-item><p>We need to develop a tool to help us calculate trace consistency automatically.</p></list-item>
</list></p></sec>
<sec sec-type="data-availability" id="s7">
<title>Data availability statement</title>
<p>The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.</p></sec>
<sec sec-type="author-contributions" id="s8">
<title>Author contributions</title>
<p>Before writing this paper, FZ, DX, and GL have discussed the relevant details about trace consistency measurement. Afterwards, FZ wrote the paper. DX and GL revised the paper. All authors contributed to the article and approved the submitted version.</p></sec>
</body>
<back>
<sec sec-type="funding-information" id="s9">
<title>Funding</title>
<p>This work was partially supported by the National Nature Science Foundation of China under Grant 62002328, 62172299 and 62032019, the Youth Foundation of Anhui University of Technology under Grant QZ202215, and the Key Laboratory of Embedded System and Service Computing under Grant ESSCKF 2021-02.</p>
</sec>
<sec sec-type="COI-statement" id="conf1">
<title>Conflict of interest</title>
<p>The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
<sec sec-type="disclaimer" id="s10">
<title>Publisher&#x00027;s note</title>
<p>All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.</p>
</sec>
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