=Paper= {{Paper |id=Vol-1979/paper-17 |storemode=property |title=Automatic Classification to Matching Patterns for Process Model Matching Evaluation |pdfUrl=https://ceur-ws.org/Vol-1979/paper-17.pdf |volume=Vol-1979 |authors=Elena Kuss,Heiner Stuckenschmidt |dblpUrl=https://dblp.org/rec/conf/er/KussS17 }} ==Automatic Classification to Matching Patterns for Process Model Matching Evaluation== https://ceur-ws.org/Vol-1979/paper-17.pdf
    Automatic Classification to Matching Patterns
       for Process Model Matching Evaluation

                      Elena Kuss and Heiner Stuckenschmidt

                University of Mannheim, Artificial Intelligence Group



      Abstract. Business process model matching is concerned with the de-
      tection of similarities in business process models. To support the progress
      of process model matching techniques, efficient evaluation strategies are
      required. State-of-the-art evaluation techniques provide a grading of the
      evaluated matching techniques. However, they only offer limited informa-
      tion about strength and weaknesses of the individual matching technique.
      To efficiently evaluate matching systems, it is required to automatically
      analyze the attributes of the matcher output. In this paper, we propose
      an evaluation by automatic classification of the alignments to matching
      patterns. On the one hand, to understand strength and weaknesses of
      a matching technique. On the other hand, to identify potential for fur-
      ther improvement. Consequently, optimal matching scenarios of a spe-
      cific matcher can be derived. This further enables tuning of a matcher
      to specific applications.

      Keywords: business process model matching evaluation, matching per-
      formance assessment, matching patterns


1    Introduction
Conceptual models, like business process models, are widely used to document a
company’s operations. Process model matching aims in identifying semantic sim-
ilarities in business process models. Application scenarios vary strongly for exam-
ple from process model search in huge data bases [9], the automatic integration
within company merges [11] or clone detection [6]. There are many techniques for
the automatic identification of similarities in process models [4,13,17,19]. Cur-
rent process model matching techniques focus on finding similarities between
process models by comparing the label-strings of these process models.
    Overall, it can be observed that most research efforts are spent in advancing
the process matching techniques compared to the advancement of their evalua-
tion.
    The process model matching track (PMMT) at the Ontology Alignment
Evaluation Initiative (OAEI) [1] and the Process Model Matching Contests
(PMMCs) [2,3] apply different metrics to evaluate process model matching tech-
niques. These metrics allow for evaluating the performance of matching tech-
niques through a ranking. Consequently, they only provide limited information
about the performance of matching techniques, e.g., detailed information about




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In: C. Cabanillas, S. España, S. Farshidi (eds.):
Proceedings of the ER Forum 2017 and the ER 2017 Demo track,
Valencia, Spain, November 6th-9th, 2017,
published at http://ceur-ws.org
2       Elena Kuss and Heiner Stuckenschmidt

the strength and weaknesses of a matching technique. However, the progress of
process model matching techniques is strongly influenced by the available eval-
uation techniques. Important is that the evaluation techniques are “fair” and
that they can be computed efficiently, i.e., without intensive manual labor.
    In this paper, we propose a conceptually different evaluation approach. The
basis of our idea is to group the alignments of the matcher output as well as the
reference alignment into different categories. In our example we utilize five differ-
ent such categories. For each of the category, the widely-used measures precision,
recall and F-measure are computed. These metrics for each category enables us
then to analyze a matcher’s performance in greater detail. This way, we gain
insights which matcher performs well on “trivial” correspondences or can also
identify “difficult” correspondences. Among the more complex correspondences,
we learn for each individual matcher which correspondences can be found and
which are challenging.
    In the first step of the proposed evaluation method, the correspondences in
the reference alignment are assigned to the different categories. The same is done
for the matcher output in the second step. Both steps are done automatically
– no user input is required. Then, each category is treated as its own matching
problem where standard metrics can be applied.
    By automatic annotation to matching patterns, the matching problem it-
self is classified into categories. These categories divide the matching problem
into different levels of complexity. On the one hand this helps gaining insights
about the complexity of the matching task itself, on the other hand this helps
understanding strength and weaknesses of a matcher. Equally important, the
categorization helps to identify possibilities for the improvement of a matcher’s
performance.
    Furthermore, the categorization helps understanding the performance of a
matcher for specific matching tasks. Sometimes a matcher needs to satisfy dif-
ferent tasks. For example when finding similar process models in a database it
may be required to be able to identify a high fraction of correspondences which
are semantically identical. However, for some applications it is simply required
to compute a high fraction of identical labels. For an efficient evaluation it is
required that the evaluation takes the specific application scenarios into account.
    The remainder of the paper is organized as follows. In Section 2, the basis
of the process model evaluation is defined. Section 3 introduces the matching
patterns which are automatically assigned and gives examples to illustrate these
patterns. In Section 4, evaluation experiments are obtained and the results of the
evaluation by matching patterns are discussed in detail. While Section 5 gives an
overview about related work, Section 6 concludes the paper and discusses future
work.


2   Problem Description

Definition 1 (Alignment, reference alignment, matcher output, corre-
spondence). For two process models P1 , P2 with their activity sets A1 , A2 ,
     Automatic Classification to Matching Patterns for Matching Evaluation       3

an alignment is a set consistent of activity pairs (a1 , a2 ) with a1 ∈ A1 and
a2 ∈ A2 . A reference alignment G is a subset of all possible alignments, i.e.,
G ⊆ A1 × A2 . Similarly, a matcher output O is a subset of all possible align-
ments, i.e., O ⊆ A1 × A2 . An alignment of the reference alignment is also called
a correspondence.

     The task of a matcher is to identify semantically similar alignments, i.e., to
identify the correspondences of the reference alignment. Currently, the matching
is mostly based on the label strings of the process models to be matched. Because
it is rarely possible to reach a perfect matching, i.e., O = G, the matcher output
needs to be evaluated. There is a whole body of literature on process model
matching techniques. They have all in common that the evaluation focuses on
grading the evaluated matchers. Thus, the evaluation is designed to provide a
matcher’s rank within a group of matchers. However, most evaluation methods
are not designed to provide a detailed analysis of an individual matcher output.
To obtain such detailed information, currently it is required to manually process
and interpret the matcher output to identify possibilities for improvement. In
contrast, we propose a new evaluation technique which provides such information
for an individual matcher output, without the need for manual processing. Our
proposed category-dependent evaluation has the following properties:
 – informs about the data set, e.g., the complexity of the matching task
 – assesses the reference alignment indirectly, e.g., quality and quantity of man-
   ual annotations
 – identifies characteristics as well as strength and weaknesses of a matcher
 – enables to optimize a matcher to specific application scenarios.
    By identifying the strength and weaknesses of a matcher, the proposed eval-
uation technique may aid the progress of matching techniques. This becomes
clearer with the experiments in Section 4.


3   Automatic Classification to Matching Patterns
Figure 3 illustrates the conceptual structure of the automatically assigned cat-
egories. The matching problem is divided into “trivial” and “non-trivial” align-
ments. “Trivial” alignments are any alignments which are identical after nor-
malization.

Definition 2 (Normalization). For the classification, an activity is normal-
ized, if (1) all stop words are removed, (2) stemming has been applied and (3)
case sensitivity is ignored.

Example of stop-words are “of”, “for” and “the”. Examples for stemming are
“checking” and “checks” transformed into “check”.
    “Non-trivial” alignments are all other alignments. The “non-trivial” category
consists of four sub-categories. In the following, we define these categories and
give examples.
4        Elena Kuss and Heiner Stuckenschmidt




                   Fig. 1. Structural dependencies of the categories


3.1    The Categories
The core of the evaluation via matching patterns is to automatically 1 assign
correspondences of the reference alignment as well as the computed alignments to
groups with specific attributes. After the automatically generated classification
to one of the categories, the well-known metrics precision, recall and F-measure
[14] are calculated for each of theses categories separately. As a consequence, the
matching task is divided into groups with specific attributes. In the following, we
define the categories and illustrate these with examples from the applied data
sets. The categories are chosen to provide a deeper knowledge about specific
attributes which are important features of a matching technique. Note that the
specific numbering of the categories is not related to the complexity level of the
corresponding category.

Definition 3 (Categorization, category). Let A1 , A2 be the activity sets
for two process models P1 and P2 . A categorization is a division of all possible
alignments into disjoint sets C(i), i.e., C(i) ⊆ A1 × A2 for all i with ∪i C(i) =
A1 × A2 and C(i) ∩ C(j) = ∅ for all i 6= j. Any C(i) is a category.

   In general, the categories should be chosen carefully. It is important that
the classification can be assigned automatically. Moreover, too many categories
1
    The implementation of the matching patterns, containing the automatic annotation
    can be accessed here: https://github.com/kristiankolthoff/PMMC-Evaluator/
    tree/master/src/main/java/de/unima/ki/pmmc/evaluator/annotator
     Automatic Classification to Matching Patterns for Matching Evaluation      5

lead to too few alignments in each category; too few categories lack information.
We propose the following categories (the examples are taken from the reference
alignment of the data sets of the PMMC 2015):

Category “trivial”: This category contains alignments which are identical af-
   ter normalization.

Category I “no word identical”: Alignments which have no word in com-
   mon after normalization are assigned to this category. Examples:
   Ex. 1: Evaluate – Assessment of application
   Ex. 2: Hand application over to examining board – Send documents to
      selection committee
      [The stop word “to” is ignored and not counted as an identical word.]
   Ex. 3: Talk to applicant – Do the interview
   Ex. 4: Shipping – Delivery and Transportation Preparation
   Ex. 5: Shipment – Transportation Planning and Processing

Category II “one verb identical”: Alignments which are assigned to this
   category have exactly one identical verb after normalization. No other words
   are identical. Examples:
   Ex. 6: Send documents by post – Send all the requirements to the secre-
       tarial office for students
   Ex. 7: Wait for results – Waiting for response
       [This example illustrates two specific characteristics: the verb is normal-
       ized (stemming), the stop word (in this case “for”) is ignored.]
   Ex. 8: Send acceptance – Send commitment
   Ex. 9: Check data – Check documents

Category III “one word identical”: This category consists of alignments which
   have exactly one word (but not a verb) in common after normalization. Ex-
   amples:
   Ex. 10: Talk to applicant – Appoint applicant
   Ex. 11: Hand application over to examining board – Send application
      to selection committee
      [In this example the stop word “to” is ignored.]
   Ex. 12: Apply online – Fill in online form of application
   Ex. 13: Invoice approval – Invoice Verification

Category “misc”: All other alignments, which cannot be assigned to one of
   the above categories. Examples:
   Ex. 14: Send application – Send application form and documents
   Ex. 15: Send documents to selection committee – Send application to
       selection committee
   Ex. 16: Receiving the written applications – Receive application
   Ex. 17: Time Sheet Approval – Time Sheet Permit
6       Elena Kuss and Heiner Stuckenschmidt

    The described categories vary strongly in their level of complexity. In the
following, we discuss each category with increasing complexity level of the cate-
gories. The Cat. trivial contains identical labels after normalization. Only basic
syntactical matching techniques are required to identify such correspondences.
    The Cat. misc contains all alignments which cannot be assigned to one of the
other categories. Thus, it contains only alignments which share more than one
identical word. Therefore this category is a category with less complex alignments
compared to Cat. I through Cat. III.
    Cat. II and Cat. III have a rather high complexity level, since these categories
have just one word / one verb in common. Both categories can further indicate
if a matcher produces already a high fraction of alignments if one word or the
verb between two labels are identical. Cat. I, however, is the most complex
category among the introduced categories, since these alignments have no word
in common. They have no syntactical overlap. Consequently these alignments
just have a semantic connection, like this is the case for synonyms. To identify
alignments from this category correctly, a matcher requires advanced semantic
knowledge. Note that each alignment is assigned to exactly one of these categories
exclusively, i.e., the alignments cannot be assigned to several categories.




                Fig. 2. Example of a categorized reference alignment


    Figure 2 illustrates a simplified example of a reference alignment which is as-
signed to the above described categories. The figure shows two example process
models, which illustrate the application process of Master students at two uni-
versities. A matcher’s task is to identify correspondences of one process model in
      Automatic Classification to Matching Patterns for Matching Evaluation      7

the other process model. The correspondences of this matching task are marked
with different gray scales for each of the introduced categories above. For each
introduced category there is one example in the figure. However, the Cat. misc
is illustrated with two examples of the reference alignment. Note that the illus-
trated figure is an example of a reference alignment. For the evaluation procedure
also the alignments computed by a matcher are classified to the matching pat-
terns.

3.2   Metrics for the Categories
Definition 4 (category-dependent Precision, category-dependent Re-
call, category-dependent F-measure). Let set G be the reference alignment,
O be the matcher output and C(i) be the categories. The set G(i) is the collection
of reference alignments assigned to category C(i), i.e., G(i) = G ∩ C(i) for all i.
Similarly, O(i) is the collection of correspondences computed by a matcher and
assigned to category C(i); i.e., O(i) = O ∩ C(i) for all i.
    The category-dependent Precision, cP (i), is defined as
                                         |G(i) ∩ O(i)|
                              cP (i) =
                                            |O(i)|
and the category-dependent Recall, cR(i), is given by
                                         |G(i) ∩ O(i)|
                             cR(i) =                   .
                                            |G(i)|
The category-dependent F-measure, cF M (i), is then
                                            cP (i) · cR(i)
                          cF M (i) = 2 ·                   .
                                           cP (i) + cR(i)
    Precision is the fraction of correctly computed alignments to all computed
alignments. Recall is the fraction of correctly computed alignments to all correct
correspondences (with respect to the reference alignment). Both precision and
recall are values between 0.0 and 1.0. A precision of 1.0 means that all computed
correspondences are contained in the reference alignment, i.e. O(i) ⊆ G(i). In
contrast, a recall of 1.0 means that all correspondences of the reference align-
ment are computed, i.e. G(i) ⊆ O(i). The F-measure is the harmonic mean of
precision and recall. All alignments in the reference alignment as well as the
matcher output are assigned to exactly one category exclusively, i.e. there is no
overlap between these categories. After this, precision, recall and F-measure of
the alignments of each category are calculated. That means, the categories are
evaluated separately and independently.


4     Experiments
To illustrate the insights which can be obtained by the proposed matching eval-
uation, we apply the introduced technique to the data sets and participating
8      Elena Kuss and Heiner Stuckenschmidt

matchers of the Business Process Model Matching Contest 2015 and the Pro-
cess Model Matching Track at the OAEI 2016 with its participating matching
techniques.

4.1   Setting
In the following, the data sets are described. More details about the participating
matchers and the data sets can be found at [1,2].

Birth Registration Data set (PMMC 2015) The birth registration data set
contains 36 business process model pairs, which model the process of registering
a new born child in Russia, South Africa, Germany and the Netherlands. The
models are modeled as Petri-nets.

Asset Management Data set (PMMC 2015) This data set consists of 36
model pairs of a SAP Reference Model collection which describe processes in the
area of finance and accounting. These models are event-driven process chains
(EPCs).

University Admission Data set (PMMC 2015 / PMMT 2016) This
data set contains 36 process model pairs, derived from 9 models from German
universities, which model the application process of Master students.

4.2   Results
Below, we present the results of the automatic generated matching patterns. The
matching patterns are assigned automatically to the reference alignment, as well
as to the matcher output of the matchers which participated in the PMMC 2015
and the PMMT at the OAEI 2016. Then category-dependent precision, recall
and F-measure are computed for each category separately. After application of
the matching patterns to the reference alignment as well as to the alignments
computed by the matchers, the following results are computed.

Computational results Tables 1-3 illustrate the results for each data set. The
first column provides a list of all participating matchers. They are listed in al-
phabetic order. In the second column, the F-measure (FM) over all matching
patterns is given as the micro value, i.e. it is computed over all test cases. The
remaining columns provide the category-dependent precision (cP), recall (cR)
and F-measure (cFM) for each matcher in each category. cP, cR and cFM are
macro values, independently computed for each of the matching patterns. For
each category, the tables further show in the heading the fraction of correspon-
dences from the whole data set as well as the total number of correspondences of
a category in the reference alignment. The best three matchers are highlighted in
each category. One central observation is the distribution of the correspondences
      Automatic Classification to Matching Patterns for Matching Evaluation                                                   9

 Approach     FM           Cat.                Cat. I               Cat. II             Cat. III               Cat.
                          trivial          no word iden.        one verb iden.      one word iden.             misc
                       [44.3%][103]          [29.3%][68]          [11.6%][27]          [7.3%][17]           [7.3%][17]
                     cP    cR cFM         cP    cR    cFM      cP    cR     cFM     cP    cR    cFM      cP    cR    cFM
 AML          .698   .844   .959   .862   .952   .595   .623   .833   .300   .311   .667   .372   .344   .157   .576   .183
 AML-PM       .385   .844   .963   .864   .458   .397   .334   .187   .633   .217   .045   .500   .069   .112   .970   .151
 BPLangM      .397   .939   .816   .864   –      –      –      .462   .344   .262   .152   .526   .175   .084   .348   .094
 DKP          .538   .844   .968   .867   .267   .048   .070   –      –      –      –      –      –      .136   .227   .099
 DKP-lite     .534   .844   .968   .867   –      –      –      –      –      –      –      –      –      .136   .227   .099
 KnoMa-Proc   .394   .833   .931   .845   –      –      –      .078   .133   .067   .068   .346   .092   .052   .409   .066
 KMSSS        .544   .846   1.0    .883   .450   .172   .151   .500   .289   .251   .357   .205   .164   .142   .636   .152
 LogMap       .481   .844   .978   .872   –      –      –      .467   .167   .127   .082   .372   .094   .092   .530   .110
 MSSS         .608   .844   .968   .867   .500   .069   .057   .833   .500   .489   –      –      –      .143   .091   .083
 OPBOT        .601   .978   .706   .774   .713   .468   .433   .562   .322   .290   .432   .500   .333   .128   .530   .164
 pPalm-DS     .253   .843   .986   .874   –      –      –      .053   .344   .072   .029   .410   .046   .062   .939   .086
 RMM-NHCM     .668   .954   .930   .928   .821   .374   .397   .452   .456   .292   .550   .372   .302   .178   .439   .166
 RMM-NLM      .636   .843   1.0    .881   .486   .324   .303   –      –      –      –      –      –      1.0    .091   .091
 RMM-SMSL     .543   .844   .912   .839   .778   .423   .439   .152   .311   .121   –      –      –      .087   .121   .058
 RMM-VM2      .293   .825   .767   .759   –      –      –      .044   .367   .065   .040   .372   .058   .081   .742   .110
 TripleS      .485   .843   1.0    .881   –      –      –      .077   .156   .072   .625   .179   .185   .025   .121   .029

Table 1. Results of University Admission data set (PMMC 2015 and PMMT 2016)


 Approach     FM           Cat.                Cat. I              Cat. II              Cat. III               Cat.
                          trivial          no word iden.       one verb iden.       one word iden.             misc
                       [45.9%][102]          [34.2%][76]          [0.9%][2]            [8.1%][18]           [10.8%][24]
                     cP    cR cFM         cP    cR    cFM      cP    cR    cFM      cP    cR    cFM      cP    cR    cFM
 AML-PM       .677   .996   1.0    .998   1.0    .059   .059   .667   1.0    .667   .231   .396   .219   .571   .742   .565
 BPLangM      .646   .996   .951   .970   .300   .176   .149   1.0    .500   .500   .200   .354   .161   .646   .706   .528
 KnoMa-Proc   .355   .251   .968   .367   –      –      –      .083   1.0    .119   .100   .062   .042   .220   .570   .237
 KMSSS        .579   .996   1.0    .998   –      –      –      –      –      –      .333   .062   .067   .342   .552   .297
 MSSS         .619   .996   1.0    .998   –      –      –      –      –      –      –      –      –      .417   .127   .119
 OPBOT        .639   .996   1.0    .998   .250   .026   .033   .500   1.0    .500   .286   .469   .252   .640   .891   .653
 pPalm-DS     .474   .996   1.0    .998   –      –      –      1.0    1.0    1.0    .243   .312   .161   .301   .909   .333
 RMM-NHCM     .661   .996   1.0    .998   –      –      –      –      –      –      .500   .062   .083   .667   .303   .290
 RMM-NLM      .653   .996   1.0    .998   –      –      –      –      –      –      –      –      –      1.0    .194   .217
 RMM-SMSL     .354   .990   .582   .659   –      –      –      –      –      –      .333   .177   .144   .333   .109   .089
 RMM-VM2      .603   .996   .962   .976   1.0    .059   .059   .667   1.0    .667   .131   .417   .126   .450   .612   .418
 TripleS      .578   .996   1.0    .998   –      –      –      –      –      –      .111   .062   .048   .372   .633   .324

              Table 2. Results of Asset Management data set (PMMC 2015)




in the reference alignments. This aids in understanding the complexity level of
the applied data sets.
    Table 1 illustrates the results for the University Admission data set (includ-
ing the participants of the PMMT at the OAEI 2016). As can be observed, the
University Admission data set consists of a very high fraction of trivial correspon-
dences. Almost half of the correspondences (44,3%) in the reference alignment
are trivial correspondences. It can further be observed, that most matchers focus
on identifying trivial correspondences. Just few matchers can identify a reason-
able number of complex correspondences. Similar behavior can be observed for
the Asset Management data set in Table 2 with 45,9% trivial correspondences.
Again, most matchers focus on identifying these trivial correspondences. No
matcher can achieve good results for Cat. I. For Cat. II and Cat. III there is
a similar picture. However, for the Asset Management data set, the number of
correspondences in Cat. II is too low to draw meaningful conclusions.
    For the Birth Registration data set (Table 3), there is a different observation.
75% of all correspondences are correspondences of Cat. I. This shows, that this
10      Elena Kuss and Heiner Stuckenschmidt

 Approach     FM           Cat.                 Cat. I              Cat. II             Cat. III               Cat.
                          trivial          no word iden.        one verb iden.      one word iden.             misc
                        [4.5%][26]           [75.0%][437]          [1.5%][9]           [9.9%][58]           [9.1%][53]
                     cP    cR     cFM     cP     cR    cFM     cP    cR     cFM     cP    cR    cFM      cP    cR    cFM
 AML-PM       .392   .190   .792   .239   .386   .329   .329   .071   .048   .036   .496   .336   .308   .772   .366   .382
 BPLangM      .418   .891   .594   .562   .517   .254   .314   .500   .333   .250   .554   .346   .340   .742   .253   .295
 KnoMa-Proc   .262   .563   .698   .509   .215   .279   .229   .200   .190   .100   .130   .130   .082   .519   .342   .300
 KMSSS        .385   .908   .688   .701   .791   .239   .308   –      –      –      .450   .148   .143   .773   .352   .355
 MSSS         .332   1.0    .667   .696   .973   .174   .243   –      –      –      .583   .130   .119   1.0    .144   .158
 OPBOT        .565   .882   .854   .831   .676   .422   .483   .250   .286   .152   .714   .485   .470   .688   .451   .444
 pPalm-DS     .459   .894   .875   .871   .454   .356   .354   .100   .286   .111   .452   .426   .335   .706   .587   .504
 RMM-NHCM     .456   .923   .698   .717   .717   .319   .389   .400   .190   .167   .552   .262   .261   .623   .292   .283
 RMM-NLM      .309   1.0    .443   .487   .952   .163   .223   –      –      –      .389   .130   .119   1.0    .154   .174
 RMM-SMSL     .384   .667   .292   .307   .506   .329   .346   .095   .286   .111   .304   .194   .147   .633   .390   .353
 RMM-VM2      .433   .894   .854   .805   .391   .339   .339   .050   .190   .056   .413   .432   .335   .652   .470   .469
 TripleS      .384   .445   .719   .450   .651   .268   .309   –      –      –      .433   .142   .131   .679   .367   .361

              Table 3. Results of Birth Registration data set (PMMC 2015)




data set is by far the most complex of these three data sets. Similar to the Asset
Management data set, only a low fraction of correspondences of the reference
alignment have only the verb in common (Cat. II). Furthermore, it can be ob-
served that many matchers fail in identifying the trivial correspondences of this
data set. One explanation may be the reference alignment for this data set be-
cause we find that the reference alignment of the Birth Registration data set does
not fully cover all trivial correspondences or contains wrong trivial alignments.
Another observation is that matcher need to take structural dependencies into
account, to differentiate between wrong and correct trivial alignments.
    The Cat. trivial of the Asset Management and the Birth Registration data
sets only contains correspondences which are exactly identical without any nor-
malization. This is not the case for the University Admission data set. Therefore,
we further distinguish between the kind of trivial correspondences, i.e. if these
correspondences are “identical” or “identical after normalization”; see Figure
3. We find that in the University Admission data set, about 7% of Cat. trivial
consists of correspondences which are trivial after normalization, like stemming.
This is a very small fraction and illustrates that for the detection of most corre-
spondences of this category not even a normalization is required. However, the
sub-division of Cat. trivial, helps to understand if matchers are able to detect
trivial correspondences, which require normalization.


Observations and Findings With the evaluation through matching patterns
it is possible to identify characteristics, strength and weaknesses of a matcher.
The results clearly show that most matchers focus on finding correspondences
with low complexity, i.e., Cat. trivial and Cat. misc. The matchers clearly lack
identifying complex correspondences. This is especially evident for the Asset
Management data set which contains special technical terms. For detecting non-
trivial correspondences, a matching technique requires knowledge about these
terms. It can be observed that the matcher BPLangMatch, in contrast to the
other matchers, is able to identify difficult correspondences of this specific data
set. The matcher AML achieves very good results for Cat. I (cFM of 0.623) at
      Automatic Classification to Matching Patterns for Matching Evaluation                                                               11

the University Admission data set. With this high performance for this category,
it can be expected that the matcher AML would achieve a high performance on
the Birth Registration data set. However, since this matcher did not participate
in the PMMC 2015, the results for this data set are not available. Moreover, the
matcher OPBOT achieves considerably good results for Cat. I in the Admission
data set. Therefore it is not surprising that this matcher reaches the best F-
measure on the Birth Registration data set.


Approach             University Admission                           Asset Management                           Birth Registration
             trivial    I      II   III   misc              trivial   I    II    III  misc             trivial   I     II     III  misc
              [103]   [68]    [27]  [17]  [17]               [102]  [76]   [2]   [18] [24]               [26]  [437]   [9]    [58] [53]
             FP FN FP FN FP FN FP FN FP FN                  FP FN FP FN FP FN FP FN FP FN              FP FN FP FN FP FN FP FN FP FN
AML          12    6    2   27   1   22   3   11 45     8
AML-PM       12    5   32   48 60    12 113   10 117    1    1    0 0 75    2   0 19 11      13   4    48   5 203 287   9   8 24 38      6 32
BPLangM       6   24   37   68   8   20 55     9 70    10    1    5 15 71   0   1 16 13       8   7     2   8 72 311    3   6 16 37      6 41
DKP          12    4   19   60   0   27   0   17 36    14
DKP-lite     12    4    0   68   0   27   0   17 36    14
KnoMa-Proc   12   10    1   68 24    23 41    12 134    9   209   7   0 76 13   0 15 17      69 8      12   7 463 306 10    7 35 53 15 37
KM-SSS       12    0   16   61   7   18   9   13 83     6     1   0   0 76 0    2 3 17       61 10      2   7 23 326 1      9 7 52 4 41
LogMap       12    2    0   68   4   23 39    11 92     8
Match-SSS    12    4    4   64   2   17   0   17   9   17    1 0 3 76       0   2    0   18   8   21    0 8    6 347 1      9    3   53 0 48
OPBOT         3   21   11   32   8   21 12    10 60     8    1 0 18 74      3   0   27    9 21     2    2 4 74 248 5        5   17   29 12 24
pPalm-DS     13    3    5   68 143   15 317   10 216    2    1 0 4 76       0   0   35   13 163    1    4 3 181 274 10      7   32   34 17 19
RMM-NHCM      8    3    7   42 13    16   5   11 36     9    1 0 0 76       0   2    1   17   3   15    1 7 49 295 3        7   12   43 8 37
RMM-NLM      13    0   25   45   0   27   0   17   0   17    1 0 0 76       0   2    0   18   0   18    0 13 10 352 1       9    7   53 0 46
RMM-SMSL     11   17    6   34 59    15   8   17 43    15    1 56 0 76      0   2   14   14   5   22    4 16 130 291 13     7   19   50 8 39
RMM-VM2       8   20    2   68 114   20 169   11 104    5    1 7 0 75       1   0   39   10 16     9    3 4 190 280 21      7   32   31 13 28
TripleS      13    0    0   68 52    22   2   14 51    16    1 0 0 76       0   2   19   16 56     7   25 6 60 313 1        9   10   52 7 40

Table 4. False-positive (FP) and false-negative (FN) alignments for the three data
sets and all matchers, assigned to the categories.



    However, from the three different data sets, it seems that the matchers are
optimized to the specific data sets. For example, while the matchers focus on
finding correspondences from Cat. trivial in the University Admission data set
and Asset Management data set, in contrast, at the Birth Registration data
set matchers aim at identifying correspondences from Cat. I. This can also be
observed by the number of false-positive and false-negative alignments for each
category (Table 4). The matchers compute a high number of false-positive align-
ments in Cat. I for the Birth Registration data set, i.e. the matchers aim at
identifying correspondences from this category. For the Asset Management data
set, however, most matchers do not compute alignments from Cat. I at all. This
can be explained by the fact that Cat. I is on the one hand, the most difficult
category, but on the other hand, to succeed at the Birth Registration data set
it is necessary to compute correspondences from this category. The reason is
the very high fraction of correspondences on the whole Birth Registration data
set for Cat. I (about 75%). The classification of the false-positives and false-
negatives into the categories allows a more fine-grained understanding about a
matcher’s performance. It enables to directly identify where sources for errors of
the matchers are. For example the matcher KnoMa-Proc computes a very high
number of false-positive alignments in Cat. trivial for the Asset Management
data set. The matcher RMM-SMSL misses many trivial correspondences (56)
from the Asset management data set.
12      Elena Kuss and Heiner Stuckenschmidt

5    Related work

State-of-the-art evaluation techniques mostly rely on precision, recall and F-
measure for evaluation of process model matching techniques. In [10] these met-
rics are extended to probabilistic versions with a non-binary reference align-
ment. This non-binary reference alignment contains support values obtained by
the number of annotators which identify a correspondence. This extension al-
lows a deeper understanding about a matcher’s performance, since it helps to
understand if matchers focus on identifying correspondences with high support
values (mostly obvious correspondences) or if they also can identify arguable
correspondences. Furthermore, [18] propose a prediction of the performance of
process matching techniques.
    In ontology matching, more research has been dedicated to evaluation strate-
gies [5,7,15,16,20]. Euzenat, for example, introduced semantic precision and re-
call. This extension for ontology matching techniques allows to differentiate if
the computed correspondences are related, by taking the ontological structure
into account. As a consequence, deductible alignments are evaluated. Although
it better reflects the quality of the computed alignments, it does not provide
information about the structure of correspondences a matcher can identify and
thus does not provide information about specific strength and weaknesses of
matching techniques.
    In schema matching, [12] propose synthetic scenarios to tune a schema matcher
to specific applications. The annual Ontology Alignment Evaluation Initiatives
apply synthetic data sets which allow to test matching systems on specific char-
acteristics [1]. However, these synthetic data sets are artificially generated test
cases which rely on the same resources as most matchers rely on, e.g. Word-
Net. Therefore experts generated synonyms manually, but the manual synonym
generation comes with high efforts.
    In [8], the authors explain that it is not suitable to apply matchers on syn-
thetic scenarios, since these scenarios are too artificial. It is not clear if matchers
have a similar performance on real-world data. The matching patterns, proposed
in this paper, offer the same features as synthetic data sets, but with real-world
data.


6    Conclusion

In this paper we propose a conceptually new approach to divide the matching
task as well as the matcher output into patterns with specific attributes. The pro-
posed evaluation via matching patterns provides an in-depth evaluation about a
matcher’s performance, including specific strength and weaknesses. Therefore it
allows for an application dependent evaluation, as the evaluation procedure can
aid in improving matching techniques to obtain desired attributes. The evalua-
tion procedure further is an efficient way to automatically process the matcher
output. It can help to understand what kind of false-positive and false-negative
alignments matchers generate and therefore enables for an quantitative as well
     Automatic Classification to Matching Patterns for Matching Evaluation          13

as qualitative analysis. The approach can be extended by different matching
patterns, the only limitation is that they can be assigned automatically. Fur-
thermore, all standard metrics can be applied. In future work we aim to use
the matching patterns for a prediction of the matcher’s performance for specific
data sets. We further plan to apply the evaluation technique to the participating
matchers of the next Process Model Matching Contest.


Acknowledgments. We thank Kristian Kolthoff for his work on implementing
the automatic assignment of the problem categories.


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