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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>The Joint Knowledge Graph Labs: Neuro-symbolic Reasoning in Action</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Luigi Bellomarini</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Livia Blasi</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Andrea Gentili</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Rosario Laurendi</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Eleonora Laurenza</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Emanuel Sallinger</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Bank of Italy</institution>
          ,
          <country country="IT">Italy</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>TU Wien</institution>
          ,
          <country country="AT">Austria</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>In this work, we present the Joint Knowledge Graph Labs (Joint KG Labs), a success story across diferent countries and between academic and industrial research labs. Initially founded at the University of Oxford, it now includes a number of international institutions. Yet, our main interest shall not be on organisation, but on research foci. We shall cover three of its main areas: (1) Knowledge Graphs and reasoning, (2) neuro-symbolic AI, and (3) applications, i.e., seeing these topics in action, in particular in the domain of finance and beyond.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Knowledge Graphs</kwd>
        <kwd>Neuro-symbolic AI</kwd>
        <kwd>Reasoning</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        Systems built on strong principles. The Vadalog system as well as recent versions such as Vadalog
Parallel [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] are built on strong theoretical foundations that make scalability possible. This requires
understanding efective joins in the context of KGs [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ] and heuristics [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ] as well as benchmarks
such as iWarded [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] to understand the actual performance implications in KGs. At the core of such
      </p>
      <p>
        Beyond systems – design and
interoperability. One critical element beyond the
systems themselves are principled methods to
design KGs, in particular approaches
independent of the particular KG model [
        <xref ref-type="bibr" rid="ref23 ref24">23, 24</xref>
        ].
      </p>
      <p>
        Bridging the gap between diferent KG models
(whether RDF-based, property graph-based,
relational or other) is the labs work on eficiently
evaluating SPARQL together with
Datalogbased languages [
        <xref ref-type="bibr" rid="ref25">25</xref>
        ]. Of similar importance
for interoperability are eforts of bridging
different Datalog-based languages such as Shy
and Warded Datalog± [
        <xref ref-type="bibr" rid="ref26 ref27">26, 27</xref>
        ].
principled foundations are the questions of space eficiency [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ] and the key concepts underlying
reasoning and query optimization as well as scalability [
        <xref ref-type="bibr" rid="ref14 ref15">14, 15</xref>
        ].
      </p>
      <p>
        From a principles perspective, especially interesting are the connections to long-standing theoretical
questions in the area on dependencies [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ] and schema mappings, especially those designed for tree
and graph data [
        <xref ref-type="bibr" rid="ref17 ref18">17, 18</xref>
        ]. This has far-reaching connections back to the foundations of reasoning in and
about these [
        <xref ref-type="bibr" rid="ref19 ref20">19, 20</xref>
        ] as well as management tasks such as equivalence [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ] and limits [
        <xref ref-type="bibr" rid="ref22">22</xref>
        ].
Important extensions – temporal and more. Critical to the success of KGMSs are core properties
like full recursion and existential quantification as well as extensions such as arithmetic and aggregation.
One particularly important extension is temporal reasoning, as in the Temporal Vadalog system [28, 29].
An interesting challenge is supporting existential quantification [ 30] and aggregation [31]. Critical for
supporting the community are benchmarks such as the iTemporal benchmark generation suite [32].
2. Neuro-symbolic AI – Reasoning and KGEs, GNNs and LLMs
The Joint KG Labs have as one of its main research foci the area typically called neuro-symbolic AI, that
is, bringing together symbolic – or logic-based – reasoning, and subsymbolic – or Machine Learning
(ML)-based – reasoning [33, 34]. In the area of KGs, key ML methods are Knowledge Graph Embeddings
(KGEs), Graph Neural Networks (GNNs) and of course Large Language Models (LLMs) and related
(graph) transformer-based architectures. A stylized but evocative representation of the labs’ agenda is
shown in Figure 3.
      </p>
      <p>KGEs and GNNs. Let us start with an example of how such a neuro-symbolic combinations can work.
By combining logic-based and (Knowledge Graph) embedding-based reasoning [35] one can efectively
ifnd solutions for real-world problems such as in the domain of finance, concretely companies [ 36, 37] .
More fundamentally, it is critical to design KGE methods that can capture logical constraints [38, 39],
that is, build ML models that respect domain logic [40, 41]. Similar considerations can be made for
GNNs [42]. It is important to make such ML-methods resilient to noise [43, 44].</p>
      <p>Probabilistic reasoning and rule learning. For areas where precise understanding and control of
(ML)-based reasoning is necessary, we show two of the labs’ foci. Where precise understanding of
probabilities is necessary, probabilistic reasoning such as Markov Chain Monte Carlo-based methods
are of particular interest [45, 46]. Where full understanding is necessary of the explicit underlying
knowledge, rule learning methods can fulfill this role [ 47, 48].</p>
      <p>LLMs. While many form of ML are interesting and relevant, of particular current importance are of
course Large Language Models and neuro-symbolic uses of these. One particularly interesting one is
the lab’s approach to semantic aware query answering with LLMs Semantic-aware query answering
with Large Language Models [49].</p>
      <sec id="sec-1-1">
        <title>Reasoning</title>
        <p>Reasoning</p>
        <p>Tasks</p>
        <p>Left brain
Logic Symbolic Reasoning
Extensional</p>
        <p>Knowledge</p>
        <p>LogicReasoner
tobuildareasoninggraphbasedon</p>
        <p>extensionalknowledgeand
formalizeddomainexperience</p>
        <p>ChaseGraph
thefullreasoninggraph,thebridgeto
subsymbolicreasoners</p>
        <p>Temporal
toquantifyover
occurrencepatternsoffactsthroughtime
Provenance
toaugmentchasegraphwithXAImetadata
Embedder
toassociateinputfacts
tovector-basedrepresentations
Adapters
toreaddatafromavarietyofexternalsources
(RDBMs,graphDBMSs,RDFstores,OLAPstoresand
DWHs,NoSQLstores,theWeb,…)</p>
        <p>Top brain
to setup reasoning tasks</p>
        <p>QueryAnswering
KGMS
Chase Graph</p>
        <p>Provenance</p>
      </sec>
      <sec id="sec-1-2">
        <title>Temporal Embedders</title>
        <p>Reactive
Adapters ML bridge</p>
        <p>Bottom brain
ReasoningModes and</p>
        <p>Interactions
AITechnologiesinuse
StatisticalReasoning</p>
        <p>Other/custom
Right brain
Subsymbolic Reasoning</p>
        <p>Intensional
Knowledge
SubsymbolicReasoner
tobuildasubsymbolic(statisticalor
neural)modelfromthechasegraph
anddelegatespecializedreasoners</p>
        <p>NeuralNetworkReasoner
toapplyneuralnetworks,e.g.,recurrent
neuralnetworks,LSTM,GNN,etc.</p>
        <p>MarkovLogicProbabilisticReasoner
toapplyexpressiveprobabilistic
reasoningbasedonavariantsofMarkov</p>
        <p>LogicNetworks
MarkovRandomFieldsReasoner
toapplyefficientandlightprobabilistic
reasoningbasedonHinge-LossMRFs
Reactive
toquantifyoverchangesoccurringin
extensionalandintensionalknowledge
toenableincrementalreasoning
MLBridge
totrainMLmodelsfromreasoningresults,ortouse
MLmodelstoprovideextensionalknowledge</p>
      </sec>
    </sec>
    <sec id="sec-2">
      <title>3. Applications – Finance and Beyond</title>
      <p>The key application area of the Joint KG Labs is finance and economics. Core applications include a
manifold of using the Vadalog system for financial scenarios [ 57], including interesting meetings points
on topics such as company takeovers at the interface between computer science and economics [58].</p>
      <p>Fundamental topics include distributed computation in financial KG scenarios [ 59], mining of financial
knowledge for KGs [60], and KG-based anti-money laundering [61]. Of special interest are two areas,
the emergency reaction of the labs to the COVID-19 crisis [62, 63] and a major focus on KGs and
neuro-symbolic AI for blockchains and smart contracts [64, 65, 66, 67, 68, 69].</p>
      <p>Further key applications. Further key topics of the labs are privacy and confidentiality [70, 71, 72],
legal [73] and critical fields like healthcare [74, 75, 76, 77], enterprise architecture, in particular KG-based
modeling [78, 79, 80, 81], and education [82, 83].</p>
      <p>Acknowledgements. This work was supported by the Vienna Science and Technology Fund
(WWTF) [10.47379/VRG18013, 10.47379/NXT22018, 10.47379/ICT2201] and the Austrian Science Fund
[10.55776/COE12].</p>
    </sec>
    <sec id="sec-3">
      <title>Declaration on Generative AI</title>
      <p>The authors have not employed any Generative AI tools for writing this paper.
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