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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Towards a Standardized Description of Semantic Web Machine Learning Systems</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Fajar J. Ekaputra</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Laura Waltersdorfer</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Anna Breit</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Marta Sabou</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Semantic Web Company</institution>
          ,
          <addr-line>Vienna</addr-line>
          ,
          <country country="AT">Austria</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>TU Wien</institution>
          ,
          <addr-line>Vienna</addr-line>
          ,
          <country country="AT">Austria</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>WU Wien</institution>
          ,
          <addr-line>Vienna</addr-line>
          ,
          <country country="AT">Austria</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>In this paper, we report on our proposed approach towards a standardized description for systems combining machine learning (ML) components with techniques developed by the Semantic Web (SW) community (SWeMLS), which is one of lessons learned from our large-scale survey (476 papers) on the topic. We elaborate the key information that should be described of SWeMLS and selected methods to support its documentation.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;neuro-symbolic systems</kwd>
        <kwd>semantic web</kwd>
        <kwd>machine learning</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>1. Introduction
2. Relevant SWeMLS information
In order to adequately represent SWeML Systems, we identify four categories of relevant system
information: (i) System Settings, (ii) System Overview, (iii) System Details, and (iv) System
Evaluation, which will be briefly described in the following.</p>
      <p>System Settings To estimate the applicability of a presented approach, the description of
the domain in which a SWeMLS was evaluated is essential. The targeted task should both
be described from the use-case side –if applicable– i.e., which specific problem is being solved
(e.g., drug-drug-interaction prediction) as well as from the framing of the problem in the system
setting (e.g., link prediction task). Finally, explicitly stating the development maturity of the
presented system helps the reader to estimate its state of adaptation as well as its reliability.
System Overview Depicting the general processing flow information through the presented
system facilitates common understanding of the main processes, without diving into too much
detail. Special focus should be laid to distinct and describe the main components in this
processing flow, being processing units, i.e., Machine Learning components and Reasoning
modules, as well as the data structures (e.g., symbolic data such as KGs, or non-symbolic data
such as embeddings) on which the processing units operate. Finally, it is essential to highlight
possible diferences in these processing flows in diferent phases of the system, e.g., during
training and deployed solution.</p>
      <p>System Details To further describe the aforementioned ML components in more detail, the
authors should provide information about the model architecture including the base models
used (e.g., BERT-base), additional modules (e.g.cross-attention layer), as well as development
and training details such as the training procedure (e.g., distantly supervised), loss function and
utilized optimizers. For the SW components characteristics such as size and formalism of the
SW resource are interesting. Furthermore, the type (e.g., taxonomy / ontology) as well as their
semantic exploitation (e.g., only labels / one type of relation are used) provide highly useful
information. Finally, any used semantic processors (e.g., reasoners) should be well documented.
System Evaluation To increase the reproducibility, evaluation details need to be captured and
reported such as pre-processing steps (e.g., hyperparameter tuning), final model parameters ,
hardware specifications and auditability, such as relevant context information on the system
lifecycle, starting from the design phase to the operating system.
3. Methods for SWeMLS Documentation
This section describes selected methodologies to facilitate describing and documenting SWeMLS
based on the identified relevant information (cf. Section 2).</p>
      <p>supervised; self-supervised;
semisupervised; unsupervised; reinforcement</p>
    </sec>
    <sec id="sec-2">
      <title>TrainingType</title>
      <p>labels; hierarchical rels; simple
rels; complex structures</p>
    </sec>
    <sec id="sec-3">
      <title>SymbolUsage</title>
      <p>low (scripts, prototype);
medium (beta, demo); SystemMaturity
high (stable, enterprise, tool)</p>
      <p>Reasoner; SPARQL query engine</p>
      <p>Classical ML: Bayesian; KNN; SVM;
Decision Trees; Mixture Models; Regressions;</p>
      <p>Markov-process Models; Clusterings; Dim.</p>
      <p>Reduction; Formal Concept A.; Rule
Learning; Topic Models; SOM; Genetic</p>
      <p>Algorithms; Factorization Machines
Deep Learning: Transfomers; LSTMs; Trad.</p>
      <p>RNN Models; Trad. CNN; GAN; Plain
Encoder-based; Trad. FFNN; Matrix</p>
      <p>Factorization</p>
      <p>Graph Deep Learning: Translational
Distance; Rec. GNN; Conv. GNN; Graph</p>
      <p>AutoEncoders; Graph FFNN
1..1
1..1
1..1
0..N
1..N</p>
    </sec>
    <sec id="sec-4">
      <title>System</title>
      <p>1..N
1..N</p>
    </sec>
    <sec id="sec-5">
      <title>Processor</title>
    </sec>
    <sec id="sec-6">
      <title>Processing</title>
    </sec>
    <sec id="sec-7">
      <title>Engine</title>
    </sec>
    <sec id="sec-8">
      <title>Model</title>
    </sec>
    <sec id="sec-9">
      <title>Instance</title>
    </sec>
    <sec id="sec-10">
      <title>Statistical</title>
    </sec>
    <sec id="sec-11">
      <title>Model</title>
      <p>Legend:</p>
    </sec>
    <sec id="sec-12">
      <title>Symbolic Model</title>
      <sec id="sec-12-1">
        <title>1..N object properties</title>
        <p>with cardinality
1..1
1..1
1..1
1..1</p>
      </sec>
    </sec>
    <sec id="sec-13">
      <title>Symbol</title>
      <p>subsumption
(subClassOf)</p>
    </sec>
    <sec id="sec-14">
      <title>Domain</title>
    </sec>
    <sec id="sec-15">
      <title>Task</title>
    </sec>
    <sec id="sec-16">
      <title>Pattern</title>
    </sec>
    <sec id="sec-17">
      <title>SemanticWeb</title>
    </sec>
    <sec id="sec-18">
      <title>Resource</title>
      <p>General; Admin. &amp; Politics; Geography &amp;
Economics; Human Culture &amp; Education;
Natural Sciences; News &amp; Social Media;
Production of Goods; Software &amp; Tech; Other
Text: Analysis; Annotation; QA &amp;
conversational; Information Extraction;
Information Retrieval; Other
Graph: Extension; Creation; Alignment; Other
Image and Video; Other
Documentation properties:
Pattern sub-classes:
- Atomic Pattern - T-Pattern - I-Pattern
- Fusion Pattern - Y-Pattern - Other
SWResourceType:
Thesaurus; Taxonomy; Ontology;
Dataset; KB; Linked dataset; KG
SWResourceSize:
&lt;500; 500 -1K; 1K-10K; 10K-100K;
100K-500K; 500K-1M; &gt;1M
SWResourceFormalism:
owl / owl-2; rdf/rdf-s; other</p>
    </sec>
    <sec id="sec-19">
      <title>Data</title>
      <p>indirect relations via
SHACL constraints</p>
      <sec id="sec-19-1">
        <title>Documentation - infrastructure - process-steps</title>
        <p>- software - parameter
- data - evaluation metrics
- data-split - provenance</p>
        <p>For describing the overall SWeMLS, we propose the usage of the
SWeMLS classification system</p>
        <p>
          introduced in [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ]. For this framework, we reuse a number
of concepts introduced by van Bekkum et al. [
          <xref ref-type="bibr" rid="ref5">5</xref>
          ], including Instance, Model, and their
subconcepts, and add a number of classes and properties related to SWeMLS to align the classification
system with the main characteristics described in Section 2. Therefore, the classification system
provides guidance on what information should be provided when describing such systems,
as well as a unified and machine-readable way to document SWeMLS. For the most common
processing flows, we further provide a set of re-usable patterns. We formalized the classification
of SWeMLS as an ontology and provide instances identified during the SMS (cf. Figure 2). The
1
complete documentation of the ontology is available online .
        </p>
        <p>Describing SWeMLS Processing Flows</p>
        <p>
          As the processing flow forms one of the most
essential parts in understanding SWeMLS, great efort should be put in its documentation. To
facilitate the description, we propose a visual representation based on existing boxologies, as
they provide an intuitive way of abstraction and documentation. The boxology used in our
conducted SMS is built on the framework introduced in [
          <xref ref-type="bibr" rid="ref6">6</xref>
          ] which proposes algorithmic modules,
i.e. inductive (ML) or deductive (KR), and data structures, i.e., symbolic (such as semantic entities
or relations) or non-symbolic (such as text, images, or embeddings) (cf. Figure 1). The modular
design patterns of [
          <xref ref-type="bibr" rid="ref5">5</xref>
          ] additionally provides the possibility to describe actors and processes.
Describing SWeMLS Auditability
        </p>
        <p>
          The aim of documenting the auditability characteristics
of SWeMLS, is to increase the transparency of design decisions and operational details. For the
ML design phase, Naja et al. [
          <xref ref-type="bibr" rid="ref7">7</xref>
          ] propose a semantic framework to capture and manage traces
1http://semantics.id/semsys/ns/swemls/index-en.html
for accountability and audit purposes. However, there are neither considerations for the entire
lifecycle, nor for SWeMLS. To overcome this gap, we have introduced a SWeMLS lifecycle [
          <xref ref-type="bibr" rid="ref8">8</xref>
          ]
to achieve a common view and make system interactions explicit. The model is divided into
three perspectives: ML resource, SW resource and Application. Both types of resources have a
Design and Operation Phase with various steps. The framework can support the identification
of design and operation traces to increase the auditability of SWeMLS.
4. Conclusion and Future Work
SWeMLS are used to solve problems in diverse research fields proving their broad applicability.
Domain experts and AI researchers, however, are hampered by the lack of standardized system
description. This paper identify 1) essential system information to foster common understanding
and comparability of approaches and 2) diverse methods to support documentation as a basis
towards a standardized approach to describe and document SWeMLS.
        </p>
        <p>Future Work. We plan to extend our classification system and to further enhance the
machine-readability of the descriptions (e.g., via Open Research Knowledge Graph initiative)
and propose an evaluation framework to assess the level of auditability of such systems.
Acknowledgments This work is supported by the FFG Project OBARIS (Grant Agreement
No 877389).</p>
      </sec>
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