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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Evaluating Ontology Matchers on Real-World Financial Services Data Models</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>n Portis</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>iko P</string-name>
          <email>heikog@informatik.uni-mannheim.de</email>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Data and Web Science Group, University of Mannheim</institution>
          ,
          <country country="DE">Germany</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>SAP SE Product Engineering Financial Services</institution>
          ,
          <addr-line>Walldorf</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Financial data in enterprises is often stored using di erent data models, yet, it needs to be integrated in order to foster comprehensive evaluations. Conceptually, each of those data models can be understood as an ontology, and automated ontology matching can be applied as a rst step towards data integration. In this paper, we analyze the performance of existing ontology matching tools for matching nancial data models. The data has been provided by SAP SE and consists of real data schemas that are used in the nancial services area and mappings between them. We have created ve data sets by translating enterprise data schemas to ontologies and expert mappings to ontology alignment gold standards. We evaluate state of the art ontology matchers on our newly created data set. Our experiments show that current matching systems struggle to handle enterprise data sets and achieve signi cantly lower scores compared to data sets of other evaluation initiatives.</p>
      </abstract>
      <kwd-group>
        <kwd>Ontology Matching</kwd>
        <kwd>Ontology Alignment</kwd>
        <kwd>Data Integration</kwd>
        <kwd>Data Management</kwd>
        <kwd>Financial Services</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        For nancial services enterprises, an understanding of the company's nancial
standing as well as its risk exposure is crucial for business decisions. Naturally,
there is an endogenous motivation to federate data. Additionally, regulators
emerge to be an exogenous driver for this process by obligating nancial
institutions to report risk KPIs in a timely manner and even by regulating the IT
infrastructure (like BCBS 2392 [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]). To handle the need of data federation and
reporting, all individual data schemas of di erent software components have to
be reconciled into one holistic view of the company. The required mappings
between the data models require a high amount of manual work to be carried out
by well-paid domain experts. Automatic or semiautomatic support during this
process can help businesses in tackling these challenges in an e cient way.
      </p>
      <p>
        Studer et al. de ne an ontology as \a formal, explicit speci cation of a shared
conceptualization" [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ]. Ontology matching or ontology alignment is the
nontrivial task of nding correspondences between entities of a set of given ontologies
[
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. The matching can be performed manually or through the use of an automated
matching system. For systematically evaluating the quality of such matchers, the
Ontology Alignment Evaluation Initiative (OAEI) has been running campaigns
[
        <xref ref-type="bibr" rid="ref3">3</xref>
        ] every year since 2005.
      </p>
      <p>
        Ontologies have already been used in enterprise settings before [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] { but
despite advances in ontology matching, research in this area has not yet been
applied in the corporate world where it could be of use for instance for data
integration.
2
2.1
      </p>
      <p>Approach</p>
    </sec>
    <sec id="sec-2">
      <title>Ontologies as Data Structure Descriptor</title>
      <p>Concepts and data structures can be described using various notations and
syntaxes. At SAP Financial Services, for example, data sources and data
consumption layers are described, among others, by conceptual data models, physical
data models, API documentation, or simply by SQL DDL statements.
Depending on the notation abstraction chosen, the expressiveness varies. Ontologies can
be used to describe data structures, since they are more expressive than the
aforementioned notations.</p>
      <p>
        In a rst step, the available data was collected, and data structures were
translated into ontologies using the Web Ontology Language (OWL). In a second
step, the known mappings were transformed into the alignment format as de ned
by the Alignmnet API [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ] which is also used by the OAEI. This process is
described in the following subsection. The data is further explained in subsection
2.3. The resulting data sets follow an open format and can be processed by
regular ontology matchers.
2.2
      </p>
    </sec>
    <sec id="sec-3">
      <title>Transformation of Data Schemas</title>
      <p>
        To address the problem of heterogeneity of notations, all schemas were
transformed into ontologies by schema-speci c adapters. We have adopted the
approach for translating entity relationship models to ontologies introduced in [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ],
and extended it to account for model-speci c idiosyncrasies. The semantically
richest data structures used here are conceptual data models. Generally, entities
are translated to classes, attributes are translated to datatype properties with
a maximal cardinality of 1 and with the corresponding class as domain,
relationships are translated to object properties, and inheritances are directly taken
into account using rdfs:subClassOf. In addition, mandatory attributes were
assigned the restriction of a minimal cardinality of 1 and key elds were marked
using owl:hasKey which was introduced in OWL 2. Similarly, the cardinalities
of relationships were translated into the ontology by using restrictions. Labels
and de nitions can also be found in the resulting ontology whenever they are
available in the original source structure. This process was likewise applied in a
similar fashion to the other data structures evaluated here where applicable.
      </p>
    </sec>
    <sec id="sec-4">
      <title>Data</title>
      <p>The data has been provided for research by SAP SE. The SAP Financial Services
Data Platform (FSDP) is a solution with the purpose to help nancial
institutions with their data management. It includes a semantically rich conceptual
data model (CDM) and a performance optimized physical data model (PDM)
that can be deployed on a column-based database. As analytical (OLAP) and
transactional (OLTP) applications run on the platform, inbound and outbound
mappings are required. Data sources and consumers are mapped to the CDM.
All mappings used here were manually created by multiple experts from the
banking and insurance domain within SAP and map to the FSDP CDM.</p>
      <p>The rst data set (D1) is derived from the mapping between the conceptual
and the physical data model of FSDP. This is the largest data set. Because of
performance improvements and implementation adaptions, the entities of the
models are di erent. The second data set (D2) consists of a mapping between
the FSDP CDM and a regulatory reporting application which brings its own
data model. The third data set (D3) maps between the FSDP CDM and an
SAP accounting solution. The fourth data set (D4) is a mapping between the
FSDP business partner and the business partner of SAP ERP. The last data set
(D5) maps between a loans management system and FSDP. Data sets D2, D3,
and D5 are work in process and only the mapped structures were kept in the
corresponding ontology. Data sets D1 and D4 are complete. Table 1 gives an
overview over the data sets used.
For a rst analysis, all OAEI 2018 matchers were ran on the data set. In addition,
a simple string matcher3 has been used as baseline. The individual matcher
performance is given in Table 2. For an overall statistic, macro average was
chosen due to the di erent size and di culty of the data sets. Macro averages can</p>
      <sec id="sec-4-1">
        <title>3 BaselineStringMatcher of the MELT framework [6].</title>
        <p>
          be found in Table 3. All statistics were calculated using the MELT framework4
[
          <xref ref-type="bibr" rid="ref6">6</xref>
          ].
        </p>
        <p>
          Out of the matchers evaluated, only 5 matchers returned non-empty
alignments. Out of those, ALOD2Vec [
          <xref ref-type="bibr" rid="ref10">10</xref>
          ], LogMap Light [
          <xref ref-type="bibr" rid="ref7">7</xref>
          ], and Kepler [
          <xref ref-type="bibr" rid="ref8">8</xref>
          ] were the
only matchers to nd a non-empty alignment for all data sets.5 Kepler performs
best in terms of F1. It is outperformed by LogMap Light when using macro recall
as benchmark.
        </p>
        <p>Early experiments indicate that current matchers struggle to match real
world industry data schemas. Likely explanations are missing background
knowledge, shallow and weakly structured ontologies, and potential over tting to
publicly available benchmarks. In addition, most OAEI data sets and matchers focus
on a 1-1 alignment arity while the data sets evaluated here are more complex.
While the current prototypical set-up shows how ontology matching can be
applied in a real enterprise setting, there are still many challenges that need to be
addressed. The current data sets presented in this paper give a rst indication
of the performance of current state of the art matchers on real nancial services
data models. However, the data sets are yet small and incomplete. We plan to
extend the current data base by increasing the amount of data and to improve</p>
      </sec>
      <sec id="sec-4-2">
        <title>4 https://github.com/dwslab/melt/</title>
        <p>5 Note that all matchers in Table 2 could process each data set { i.e., the problems
are rather semantic than technical.
its quality. When the data base is grown to a more signi cant size and a high
level of quality can be ensured, we consider o ering a blind alignment track
at the OAEI. Since the results show that nancial services data models
cannot be matched without background knowledge, future work will also focus on
evaluating suitable sources of background knowledge, and on developing robust
matchers that can handle loosely structured data schemas.</p>
        <p>Acknowledgements. Acknowledgements go to Gaurav Sharma and Stephan
Schub for helping compiling the mappings and overcoming technical obstacles.</p>
      </sec>
    </sec>
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