Linking Justifications in the Collaborative Semantic Web Applications

Rakebul Hasan and Fabien Gandon, INRIA

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Outline

• Context• Linked Justifications• The Ratio4TA Vocabulary• An Example Scenario• Related Work• Future Work

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Collaborative Semantic Web Platforms

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84 articles modified per minute

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DBpedia-Live keeps DBpedia in synchronization with Wikipedia

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Ever changing interlinked dataspace

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• Results are difficult to understand by the end users

• Applications need to provide explanations along with the flow of information

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• Justification: metadata about why a conclusion has been drawn

• Justifications themselves can be RDF data distributed across the Web

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Linked Justifications

• Applying the very approach of linked data to publish justifications– Use URIs as names of things (justifications and

their components)– Use HTTP URIs– Provide useful information on lookups– Include links to the related URIs

(justifications/resources)

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• Abstraction of justifications to provide explanation; navigation between explanations

• Tracing the origin of inferences– DBPedia live and the chains of dependent

inferences

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The Ratio4TA Vocabularyhttp://ns.inria.fr/ratio4ta/v1/

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An Example Scenario

AcadWiki:Bob

AcadWiki:ComputerScientistrdf:type

AcadWiki:Scientistrdf:type

rdfs:subClassOf

GeoWiki:London

GeoWiki:UnitedKingdom

GeoWiki:isPartOf

GeoWiki:England

GeoWiki:isPartOf

AcadWiki:birthPlace

AcadWiki:birthPlace

GeoWiki

AcadWiki

GeoWiki:isPartOf

AcadWiki:birthPlace

Academician Locator

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Data

Justifications

AcadWiki:Scientist AcadWiki:ComputerScientistrdfs:subClassOf

AcadWiki:Bob AcadWiki:ComputerScientistrdf:type

AcadWiki:Bob GeoWiki:LondonAcadWiki:birthPlace

AcadWiki:Bob AcadWiki:Scientistrdf:type

r4ta:justifies r4ta:justifies

r4ta:antecedentr4ta:antecedent

r4ta:justifies

r4ta:justifies

AcadWiki:Bob GeoWiki:UnitedKingdomAcadWiki:birthPlace

r4ta:justifies

r4ta:antecedent

GeoWiki:London GeoWiki:UnitedKingdomGeoWiki:isPartOf

r4ta:justifiesr4ta:antecedent

AcadWiki

GeoWiki

Academician Locator

Bob’s birthplace is UK because Bob was born in

London and London is part of UK

London is part of UK because London is part of

England and England is part of UK

Bob was born in London

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• Named graphs– Referencing triples/graphs– Grouping justification related triples

J. J. Carroll, C. Bizer, P. Hayes, and P. Stickler. Named graphs, provenance and trust. In Proceedings of the 14th international conference on World Wide Web, WWW ’05, pages 613–622, New York, NY, USA, 2005. ACM.

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#graph for an inferred triple aloc:t1 { AcadWiki:Bob AcadWiki:birthPlace GeoWiki:UnitedKingdom.}

#graph justifying the assertion of an inferred triple aloc:j1 { aloc:j1 rdf:type Justification. aloc:j1 r4ta:justifies aloc:t1. aloc:j1 r4ta:antecedent AcadWiki:j4. aloc:j1 r4ta:antecedent GeoWiki:j1. aloc:t1 rdf:type r4ta:InferredAssertion. aloc:t1 r4ta:inferredByRule aloc:pobRule.}

Link to the triple

Link to justifications

Link to rule

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Example SPIN Rule

• Explanation for RDFS– Type propagation– Property property propagation– subClassOf transitivity – subPropertyOf transitivity– Domain inference– Range inference

@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .@prefix sp: <http://spinrdf.org/sp#> .@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .@prefix owl: <http://www.w3.org/2002/07/owl#> .@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .

_:b1 sp:varName "A"^^xsd:string .

[] a sp:Construct ; sp:templates ([ sp:object _:b2 ; sp:predicate rdf:type ; sp:subject _:b3 ]) ; sp:text """PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>CONSTRUCT { ?this a ?B .}WHERE { ?A rdfs:subClassOf ?B . ?this a ?A .}"""^^xsd:string ; sp:where ([ sp:object _:b2 ; sp:predicate rdfs:subClassOf ; sp:subject _:b1 ] [ sp:object _:b1 ; sp:predicate rdf:type ; sp:subject _:b3 ]) .

_:b2 sp:varName "B"^^xsd:string .

_:b3 sp:varName "this"^^xsd:string .

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>

CONSTRUCT {?this rdf:type ?B}WHERE { ?A rdfs:subClassOf ?B. ?this rdf:type ?A}

http://www.inria.fr/wimmics/corese/rules/typeprop

Generic HTTP URIs for rules

SPARQL Inferencing Notation (SPIN)http://spinrdf.org/this

A

Brdf:type

rdfs:subClassOf

rdf:type

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• Consuming Linked Justifications– Transforming to human understandable

presentation for explanation– Navigation between related explanation allowing

follow-your-nose principle– Tracing the origins of chains of inferences

(reasoning/truth maintenance)

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Related Work

• Laconic and precise justifications [Horridge et al., 2008]– fine-grained subclasses of justifications (laconic justifications

and precise justifications)– algorithm to compute laconic justifications– our focus is on publishing and consuming distributed

justifications

• Proof Markup Language [McGuinnes et al., 2007]– provenance, information about information manipulation

steps and trust– we have a narrower focus: justifications

•M. Horridge, B. Parsia, and U. Sattler. Laconic and precise justifications in owl. In Proceedings of the 7th International Conference on The Semantic Web, ISWC ’08, pages 323–338, Berlin, Heidelberg, 2008. Springer-Verlag.•D. McGuinness, L. Ding, P. Da Silva, and C. Chang. Pml 2: A modular explanation interlingua. In In AAAI 2007 Workshop on Explanation-aware Computing, 2007.

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• Reasoning, explanation, reason maintenance and semantic wikis [Kotowski and Bry, 2010]– Explanation in incremental development of knowledge

bases– reason maintenance: efficient knowledge base updates– do not discuss representation

• Linked data and provenance in biological data webs [Zhao et al., 2009]– design patterns to encode provenance information

using named graphs•J. Kotowski and F. Bry. A perfect match for reasoning, explanation and reason maintenance: Owl 2 rl and semantic wikis. In Proceedings of 5th Semantic Wiki Workshop, Hersonissos, Crete, Greece (31st May 2010), 2010.•J. Zhao, A. Miles, G. Klyne, and D. Shotton. Linked data and provenance in biological data webs. Briefings in bioinformatics, 10(2):139–152, 2009.

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Provenance, Justification, Explanation

• Justifications: Why someone holds a belief, explanation of why the belief is true, how one knows what one knows. – Wikipedia – Justifications justify why conclusions are drawn.

• Provenance: “sources of information, such as people, entities, and processes, involved in producing, influencing, or delivering a piece of data or a thing in the world”. – W3C Provenance ontology

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Provenance, Justification, Explanation

• Explanation: sets of statements to describe a set of facts in order to clarify the causes, context, and consequences of those facts. – Wikipedia– Main purpose is better understanding through an

objective explanation.

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Future Work

• How other provenance vocabularies can be used together– Combine with provenance vocabularies

• Provide context• Better understanding and trust [McGuinnes et al., 2007]

• W3C Provenance Model– A core data model for provenance– Ratio4TA as a specialization of the W3C PROV Ontology (PROV-O)

• r4ta:Assertion, r4ta:InferredAssertion – prov:Entity• r4ta:Justification – prov:Trace, prov:Account, prov:ProvenanceContainer• r4ta:InferenceRule – prov:Plan• r4ta:inferredByRule – prov:hadPlan, prov:Activity• r4ta:justifies – prov:traceTo, prov:qualifiedTrace• r4ta:antecedent – prov:specializationOf

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• Summarization of justifications

Rules for finding components in the graphs of justification graphs

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• Level of granularity– Single triple– Set of triples• how to deal with overlapped triples in this level

• Efficient storage and query– Huge number of graphs

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Thank Youhttp://ns.inria.fr/ratio4ta/v1/

http://kolflow.univ-nantes.fr/

Ratio4TA

http://wimmics.inria.fr/