<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Archiving and Interchange DTD v1.0 20120330//EN" "JATS-archivearticle1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Towards Visually Monitoring Multiple Perspectives of Business Process Compliance⋆</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>David Knuplesch</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Manfred Reichert</string-name>
          <email>manfred.reichertg@uni-ulm.de</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Akhil Kumar</string-name>
          <email>akhilkumar@psu.edu</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Institute of Databases and Information Systems, Ulm University</institution>
          ,
          <country country="DE">Germany</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Smeal College of Business, Pennsylvania State University</institution>
          ,
          <addr-line>PA</addr-line>
          ,
          <country country="US">USA</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>A challenge for enterprises is to ensure conformance of their business processes with imposed compliance rules. Usually, the latter may constrain multiple perspectives of a business process, including control ow, data, time, resources, and interactions with business partners. Like in process modeling, visual languages for specifying compliance rules have been proposed. However, business process compliance cannot be completely decided at design time, but needs to be monitored during run time as well. This paper introduces an approach for visually monitoring business process compliance. In particular, this approach covers all relevant process perspectives. Furthermore, compliance violations cannot only be detected, but also be visually highlighted emphasizing their causes. Finally, the approach assists users in ensuring compliant continuations of a running business process.</p>
      </abstract>
      <kwd-group>
        <kwd>business process compliance</kwd>
        <kwd>compliance monitoring</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        Correctness issues of business process models have been intensively studied for
more than a decade. While early work focused on syntactical correctness and
soundness (e.g., absence of deadlocks and lifelocks), recent approaches have
focused on how to ensure the compliance of business processes with semantic
constraints. Usually, respective compliance rules stem from domain-speci c
requirements, like, for example, corporate standards or legal regulations [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ], and
need to be ensured in all phases of the process life cycle [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ].
      </p>
      <p>In this context, approaches addressing the compliance of running business
process instances are covered by the notion of compliance monitoring [3{5]. In
general, events of running process instances need to be considered to detect and
report run-time violations of compliance rules (cf. Fig. 1). Thereby, reactive and
proactive monitoring need to be distinguished. Regarding the former, compliance
violations are reported once they have occurred. In turn, proactive monitoring
⋆ This work was done within the research project C3Pro funded by the German
Research Foundation (DFG) under project number RE 1402/2-1.</p>
    </sec>
    <sec id="sec-2">
      <title>Single</title>
    </sec>
    <sec id="sec-3">
      <title>Client ...</title>
      <sec id="sec-3-1">
        <title>Compliance</title>
      </sec>
      <sec id="sec-3-2">
        <title>Reporting</title>
      </sec>
      <sec id="sec-3-3">
        <title>Compliance Monitoring</title>
      </sec>
      <sec id="sec-3-4">
        <title>Event Bus</title>
        <p>CRM</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>System ERP</title>
    </sec>
    <sec id="sec-5">
      <title>System</title>
    </sec>
    <sec id="sec-6">
      <title>WfMS ...</title>
      <p>
        aims to prevent compliance rule violations; e.g., by suggesting appropriate tasks
that still need to be executed to meet a compliance rule. While early approaches
for monitoring compliance focused on the control
ow perspective, more and
more, additional process perspectives have been considered as well (e.g. [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]). In
particular, the data, resource and time perspectives as well as interactions with
business partners have been addressed. Other advanced work has dealt with the
traceability of compliance violations [
        <xref ref-type="bibr" rid="ref7 ref8">7, 8</xref>
        ]. However, existing approaches do not
provide a satisfactory solution that combines an expressive compliance rule
language with full traceability [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ].
      </p>
      <p>As example consider the event log from Fig. 2 that refers to an
order-to</p>
      <p>
        Fig. 2: Event log of order-to-delivery processes and compliance rules
delivery process. Compliance rule c1, which is shown on the right, is satis ed in
one case, but violated in another. In particular, the depicted log refers to two
different request items related to customers Mr. Smith and Mrs. John. These items,
in turn, trigger two di erent instances of compliance rule c1. In both cases, the
amount is greater than 10,000 e and hence a solvency check is required.
However, the latter was only performed for the request item of Mr. Smith, but not for
the one of Mrs. John (i.e., c1 is violated in the latter case). Besides the violation
of c1, compliance rule c2 is violated twice as well. While the violated instance of
c1 can never be successfully completed, the violations of c2 still can be healed by
informing the agent. The rule examples further indicate that solely monitoring
control ow dependencies between tasks is not su cient to ensure compliance
at run time. In addition, constraints in respect to the data, time and resource
perspectives of a business process must be monitored as well as the interactions
this process has with partner processes [
        <xref ref-type="bibr" rid="ref10 ref11 ref9">10, 11, 9</xref>
        ]. For example, the data
perspective of compliance rule c1 is addressed by activity request item and its data
amount. Receiving the request item, in turn, represents an interaction with a
business partner. Furthermore, the phrase by di erent sta members deals with
the resource perspective, whereas the condition at maximum three days refers to
the time perspective. To meet practical demands, compliance monitoring must
not abstract from these process perspectives.
      </p>
      <p>
        This paper sketches an approach for visually monitoring multiple perspectives
of business process compliance. For this purpose, we annotate the visual extended
Compliance Rule Graph (eCRG) language [
        <xref ref-type="bibr" rid="ref11 ref12">11, 12</xref>
        ] with text, markings and
symbols to highlight the current state of a compliance rule. The annotations not
only indicate compliance violations, but may also be utilized for recommending
the next process steps required to restore compliance. Furthermore, they allow
us to clearly distinguish between ful lled and violated instances of an eCRG.
Note that the eCRG language adequately supports the time, resource and data
perspectives as well as interactions with business partners.
      </p>
      <p>The remainder of this paper is structured as follows: The approach for visually
monitoring multiple perspectives of business process compliance is outlined in
Section 2. Section 3 concludes the paper and provides an outlook on future research.
2</p>
      <p>
        eCRG Compliance Monitoring
This paper utilizes the extended Compliance Rule Graph (eCRG) language for
compliance monitoring [
        <xref ref-type="bibr" rid="ref11 ref12">11, 12</xref>
        ]. The eCRG language is a visual language for
modeling compliance rules. It is based on the Compliance Rule Graph (CRG)
language [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ]. As opposed to the latter, the eCRG language not only focuses on
the control ow perspective, but additionally provides integrated support for the
resource, data and time perspectives as well as for the interactions with business
partners. Fig. 3 provides an overview of eCRG elements, which are applied in
Fig. 4 in order to model the compliance rules from Fig. 2.
      </p>
      <p>In the following, we sketch the approach towards visually monitoring multiple
perspectives of business process compliance at runtime. As discussed in Sect. 1,
e
c
n
eu Task
r
c
c
O
e
c
en Task
s
b
A</p>
      <sec id="sec-6-1">
        <title>Process Perspective</title>
      </sec>
      <sec id="sec-6-2">
        <title>Antecedence Consequence Basic Connectors</title>
      </sec>
      <sec id="sec-6-3">
        <title>Antecedence</title>
        <sec id="sec-6-3-1">
          <title>Task SEexqcluuesniocne</title>
        </sec>
      </sec>
      <sec id="sec-6-4">
        <title>Alternative</title>
      </sec>
      <sec id="sec-6-5">
        <title>Consequence</title>
        <sec id="sec-6-5-1">
          <title>Task SEexcqluuesniocne</title>
        </sec>
      </sec>
      <sec id="sec-6-6">
        <title>Alternative</title>
      </sec>
      <sec id="sec-6-7">
        <title>Resource Perspective</title>
      </sec>
      <sec id="sec-6-8">
        <title>Resource Nodes</title>
        <p>e
c
recnu Message</p>
      </sec>
    </sec>
    <sec id="sec-7">
      <title>O Receiver</title>
      <p>
        c
compliance monitoring is based on streams of events, which occur during the
execution of business processes, and aims to determine or prevent compliance
violations. For this purpose, we extend the approach presented in [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ] and
annotate the elements of an eCRG when processing events.
      </p>
      <p>Events The processing of event logs requires a well-de ned set of events. As the
approach enables compliance monitoring for multiple process perspectives, we
not consider only events referring to the start and end of tasks, but additionally
monitor data ow events as well as events that correspond to the sending and
receipt of messages. Furthermore, events may include temporal information as
well as information about involved resources. Table 1 summarizes the supported
event types. Each event refers to the occurrence time as well as a unique id. The
latter enables us to identify correlations between the start, end and data ow
events of the same task or message.
eCRG Markings To monitor the state of a compliance rule, we annotate and
mark eCRG elements with symbols, colors and text (cf. Figs. 5). Such a marking
of an eCRG results in an annotated eCRG highlighting whether or not the
events corresponding to a particular node have occurred so far. Furthermore,
it describes whether the conditions of edges and attachments are satis ed, are
violated or have not been evaluated yet.</p>
      <p>
        Event Processing We exemplarily describe how events are processed for an
eCRG (cf. Fig. 6) and refer to [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ] for a formal speci cation of the operational
semantics of the eCRG langauge. First, all markings are updated to the point
in time of the speci c event. Second, the e ects of the update (i.e., adapted
annotations) are propagated to succeeding as well as skipped elements. Third,
the actual event handling takes place depending on the type of the current event.
Finally, the e ects of the latter step are propagated as well.
      </p>
      <sec id="sec-7-1">
        <title>Edges</title>
      </sec>
      <sec id="sec-7-2">
        <title>Data</title>
      </sec>
      <sec id="sec-7-3">
        <title>Flow</title>
      </sec>
      <sec id="sec-7-4">
        <title>Sequence</title>
      </sec>
      <sec id="sec-7-5">
        <title>Flow</title>
      </sec>
      <sec id="sec-7-6">
        <title>Performing Resource/Data</title>
      </sec>
      <sec id="sec-7-7">
        <title>Relation Relation</title>
      </sec>
      <sec id="sec-7-8">
        <title>Attachments</title>
      </sec>
      <sec id="sec-7-9">
        <title>Time</title>
      </sec>
      <sec id="sec-7-10">
        <title>Condition</title>
      </sec>
      <sec id="sec-7-11">
        <title>Resource/</title>
      </sec>
      <sec id="sec-7-12">
        <title>Data</title>
      </sec>
      <sec id="sec-7-13">
        <title>Condition</title>
      </sec>
      <sec id="sec-7-14">
        <title>Nodes</title>
        <p>date datestart timestart
timestart–timeend dateend timeend
Task Task
performer performer
esg Sender
a
s
e Message
s
dnM date time
a
s
k
s
a
T</p>
      </sec>
    </sec>
    <sec id="sec-8">
      <title>Message</title>
      <p>date time</p>
      <p>Receiver
tno ittacaved ittacaved irnnung ltceepodm isekppd
occ
abs
future
e
m
iiittsonP D23etche2m0b2e3r
n
past
October
26th 2013
.</p>
      <p>c
rak aen
ed t
tnom .scon</p>
      <p>.
iiftesasd .tacesnon
c
.
c
e
litaevdo .tasnon</p>
      <p>c
Update
Marking</p>
      <p>Effect</p>
      <p>Propagation
Fig. 6: Processing of start, message, data and end events
≠
≠
≠
≠
≠
≠
.</p>
      <p>c
rka aen
ed t
tnom .scon</p>
      <p>.
iiftesasd .teacsnon
c
.
c
e
liteavdo .tasnon
c</p>
      <p>Effect
Propagation
&lt; 2d
&lt; 2d
&lt; 2d
&lt; 2d
&lt; 2d
&lt; 2d
&lt; 50
&lt; 50
&lt; 50
&lt; 50
&lt; 50
&lt; 50</p>
      <p>Fig. 7b illustrates the handling of a message event. In particular, the
marking of the activated message node request, which matches the event, changes
to ▶. Accordingly, the starting time is set. Start events are processed like
message events, but additionally store information about the responsible actor. Start
and message events are handled non-deterministically; i.e., the changes are
applied to a copy of the original marking. Fig. 7c shows the handling of data
events. In particular, the corresponding data ow edge is annotated with the
data value passed. Fig. 7e illustrates the handling of an end event. In particular,
the annotations of request is changed to ✓ and its ending time is set accordingly.</p>
      <p>Fig. 7g illustrates how a marking is updated to the current point in time. In
particular, the annotations of point in time nodes, which now refer to the past,
change to ✓. Finally, time conditions on running task nodes or sequence ow
edges are skipped (⨉) if they are no longer satis able (cf. Fig. 7g).</p>
      <p>According to Fig. 6, e ects of events and updates must be propagated to
indirectly a ected eCRG elements in order to ensure correct annotations (e.g.,
activation of subsequent task nodes) as well as to detect contradictory
annotations related to the data and resource perspectives. In particular, data values are
propagated from writing and reading data ow edges to dependent data object
and data container nodes (cf. Fig. 7d). In turn, resources are propagated from
task nodes to dependent resource nodes via the connecting resource edges. The
propagation fails, if a resource, data object or container node was set to a di
erent value before. In this case, the respective edge is skipped (⨉). Furthermore,
conditions and relations are evaluated as soon as possible (cf. Fig. 7d). If any
element of the eCRG corresponding to a task or message node is skipped (e.g.,
due to a failed data/resource propagation or a violated condition), the
corresponding task or message node will be skipped as well. Then, outgoing sequence
ows of completed nodes are marked as satis ed, whereas non-marked incoming
edges of already started nodes are skipped. Sequence ow edges from and to
skipped nodes are skipped as well. Task and message nodes, in turn, become
activated when all incoming sequence ows they are depending on are satis ed.
Additionally, task or message nodes will be skipped if they depend on sequence
ows that were skipped as well. Note that the latter might require skipping
further sequence ow edges, and so forth (cf. Fig. 7h). Finally, Fig. 7i provides
a marking that ful lls c1 for the request of Mr. Smith. In turn, Figs. 7h+7k
highlight con icts regarding time and resource perspectives.</p>
      <p>
        The non-deterministic processing of start and message events may result
in sets of markings. Therefore, single ful lling or con icting markings do not
imply (non-)compliance with the related rule. For this purpose, [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ] provides
mechanisms to evaluate such sets and to select the most meaningful markings.
17/2013 15:27 update
propagation of effects of initial update
37 1/7/2013 15:27 receive 124 Request
      </p>
      <p>propagation of effects of event 37
propagation of effects of event 38
customer
15,000
Fig. 7: eCRG markings and handling of events</p>
      <p>
        Summary and Outlook
Business process compliance has gained increasing interest during the last years.
Several approaches focus on compliance monitoring at run time [3{5]. However,
existing approaches do not provide a satisfactorily solution combining an
expressive language with full traceability [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ]. This paper, therefore, has sketched an
approach for visually monitoring multiple perspectives of business process
compliance. For this purpose, we utilize the extended compliance rule graph (eCRG)
language [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ] that enables the visual modeling of compliance rules with support
of the control ow, data, time, and resource perspectives as well as the
interactions with partners. We annotate eCRGs with text, colors and symbols to visually
highlight the current compliance state as well as to indicate its evolution during
process execution. Note that we formally speci ed this operational semantics of
the eCRG language in a technical report [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ]. As opposed to existing approaches,
we aim to combine full traceability with an expressive visual notation.
      </p>
      <p>
        As next step, we will investigate algorithms for eCRG-based compliance
monitoring utilizing the eCRG operational semantics we presented in [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ]. Finally,
we will provide a proof-of-concept implementation to evaluate the approach.
      </p>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          1.
          <string-name>
            <surname>Sadiq</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Governatori</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Naimiri</surname>
            ,
            <given-names>K.</given-names>
          </string-name>
          :
          <article-title>Modeling control objectives for business process compliance</article-title>
          .
          <source>In: BPM'07</source>
          ,
          <string-name>
            <surname>Springer</surname>
          </string-name>
          (
          <year>2007</year>
          )
          <volume>149</volume>
          {
          <fpage>164</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          2.
          <string-name>
            <surname>Knuplesch</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Reichert</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          :
          <article-title>Ensuring business process compliance along the process life cycle</article-title>
          .
          <source>Technical Report 2011-06</source>
          , Ulm University (
          <year>2011</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          3.
          <string-name>
            <surname>Namiri</surname>
            ,
            <given-names>K.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Stojanovic</surname>
          </string-name>
          , N.:
          <article-title>Pattern-Based design and validation of business process compliance</article-title>
          .
          <source>In: CAiSE'07</source>
          ,
          <string-name>
            <surname>Springer</surname>
          </string-name>
          (
          <year>2007</year>
          )
          <volume>59</volume>
          {
          <fpage>76</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          4.
          <string-name>
            <surname>Alles</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Kogan</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Vasarhelyi</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          :
          <article-title>Putting continuous auditing theory into practice: Lessons from two pilot implementations</article-title>
          .
          <source>Inf Sys</source>
          <volume>22</volume>
          (
          <issue>2</issue>
          ) (
          <year>2008</year>
          )
          <volume>195</volume>
          {
          <fpage>214</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          5.
          <string-name>
            <surname>van der Aalst</surname>
            ,
            <given-names>W.M.P.</given-names>
          </string-name>
          , et al:
          <article-title>Conceptual model for online auditing</article-title>
          .
          <source>Decision Support Systems</source>
          <volume>50</volume>
          (
          <issue>3</issue>
          ) (
          <year>2011</year>
          )
          <volume>636</volume>
          {
          <fpage>647</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          6.
          <string-name>
            <surname>Montali</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          , et al.:
          <article-title>Monitoring business constraints with the event calculus</article-title>
          .
          <source>ACM Trans. Intell. Syst. Technol</source>
          .
          <volume>5</volume>
          (
          <issue>1</issue>
          ) (
          <year>2014</year>
          )
          <volume>17</volume>
          :
          <fpage>1</fpage>
          {
          <fpage>17</fpage>
          :
          <fpage>30</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          7.
          <string-name>
            <surname>Ly</surname>
            ,
            <given-names>L.T.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Rinderle-Ma</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Knuplesch</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Dadam</surname>
            ,
            <given-names>P.</given-names>
          </string-name>
          :
          <article-title>Monitoring business process compliance using compliance rule graphs</article-title>
          . In: CoopIS'
          <fpage>11</fpage>
          . (
          <year>2011</year>
          )
          <volume>82</volume>
          {
          <fpage>99</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          8.
          <string-name>
            <surname>Maggi</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Montali</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Westergaard</surname>
          </string-name>
          , M.,
          <string-name>
            <surname>van der Aalst</surname>
            ,
            <given-names>W.M.P.</given-names>
          </string-name>
          :
          <article-title>Monitoring business constraints with linear temporal logic: an approach based on colored automata</article-title>
          . In: BPM'
          <fpage>11</fpage>
          . (
          <year>2011</year>
          )
          <volume>132</volume>
          {
          <fpage>147</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          9.
          <string-name>
            <surname>Ly</surname>
            ,
            <given-names>L.T.</given-names>
          </string-name>
          , et al.:
          <article-title>A framework for the systematic comparison and evaluation of compliance monitoring approaches</article-title>
          .
          <source>In: EDOC'13</source>
          ,
          <string-name>
            <surname>IEEE</surname>
          </string-name>
          (
          <year>2013</year>
          )
          <volume>7</volume>
          {
          <fpage>16</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          10.
          <string-name>
            <surname>Knuplesch</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          , et al.:
          <article-title>Towards compliance of cross-organizational processes and their changes</article-title>
          .
          <source>In: BPM'12 Workshops</source>
          , Springer (
          <year>2013</year>
          )
          <volume>649</volume>
          {
          <fpage>661</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          11.
          <string-name>
            <surname>Knuplesch</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          , et al.:
          <article-title>Visual modeling of business process compliance rules with the support of multiple perspectives</article-title>
          .
          <source>In: ER'2013</source>
          , Springer (
          <year>2013</year>
          )
          <volume>106</volume>
          {
          <fpage>120</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          12.
          <string-name>
            <surname>Semmelrodt</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Knuplesch</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Reichert</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          :
          <article-title>Modeling the resource perspective of business process compliance rules with the extended compliance rule graph</article-title>
          .
          <source>In: BPMDS'14</source>
          ,
          <string-name>
            <surname>Springer</surname>
          </string-name>
          (
          <year>2014</year>
          )
          <volume>48</volume>
          {
          <fpage>63</fpage>
        </mixed-citation>
      </ref>
      <ref id="ref13">
        <mixed-citation>
          13.
          <string-name>
            <surname>Knuplesch</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          , et al.:
          <article-title>An operational semantics for the extended compliance rule graph language</article-title>
          .
          <source>Technical Report 2014-6</source>
          , Ulm University (
          <year>2014</year>
          )
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>