1. Linking Justifications in the
Collaborative Semantic Web
Applications
Rakebul Hasan and Fabien Gandon, INRIA

2. Outline
• Context
• Linked Justifications
• The Ratio4TA Vocabulary
• An Example Scenario
• Related Work
• Future Work
1

3. Collaborative Semantic Web Platforms
2

4. 84 articles modified per minute
3

5. DBpedia-Live keeps DBpedia in synchronization
with Wikipedia
4

6. Ever changing interlinked dataspace
5

7. • Results are difficult to understand by the end
users
• Applications need to provide explanations
along with the flow of information
6

8. • Justification: metadata about why a
conclusion has been drawn
• Justifications themselves can be RDF data
distributed across the Web
7

9. 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)
8

10. • Abstraction of justifications to provide
explanation; navigation between explanations
• Tracing the origin of inferences
– DBPedia live and the chains of dependent
inferences
9

11. The Ratio4TA Vocabulary
http://ns.inria.fr/ratio4ta/v1/
10

12. An Example Scenario
AcadWiki rdf:type
AcadWiki:Scientist
rdfs:subClassOf
AcadWiki:Bob
rdf:type AcadWiki:ComputerScientist
AcadWiki:birthPlace
AcadWiki:birthPlace AcadWiki:birthPlace
GeoWiki:UnitedKingdom
GeoWiki:isPartOf
GeoWiki:London GeoWiki:isPartOf
GeoWiki GeoWiki:isPartOf
GeoWiki:England
Academician Locator
11

13. AcadWiki:Scientist AcadWiki:ComputerScientist
rdfs:subClassOf
Data AcadWiki:Bob AcadWiki:ComputerScientist
rdf:type
AcadWiki:Bob GeoWiki:London
AcadWiki:birthPlace
AcadWiki:Bob Bob was born in London
AcadWiki:Scientist
rdf:type
r4ta:justifies r4ta:justifies
r4ta:justifies
Justifications
r4ta:antecedent
r4ta:antecedent
r4ta:justifies
AcadWiki London is part of UK Bob’s birthplace is UK
because Bob was born in
because London is part of
England and England is Londonand London is
part of UK part of UK
r4ta:antecedent
GeoWiki
r4ta:antecedent
r4ta:justifies
r4ta:justifies
GeoWiki:London GeoWiki:UnitedKingdom
GeoWiki:isPartOf Academician Locator
AcadWiki:Bob GeoWiki:UnitedKingdom
AcadWiki:birthPlace
12

14. • 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. 13

15. #graph for an inferred triple
aloc:t1 {
AcadWiki:BobAcadWiki:birthPlaceGeoWiki:UnitedKingdom.
}
#graph justifying the assertion of an inferred triple
aloc:j1 {
Link to the triple
aloc:j1 rdf:type Justification.
aloc:j1 r4ta:justifies aloc:t1.
aloc:j1 r4ta:antecedent AcadWiki:j4. Link to justifications
aloc:j1 r4ta:antecedent GeoWiki:j1.
aloc:t1 rdf:type r4ta:InferredAssertion.
aloc:t1 r4ta:inferredByRule aloc:pobRule. Link to rule
}
14

16. rdf:type
B
Example SPINInferencing Notation (SPIN)
SPARQL
Rule
this rdfs:subClassOf http://spinrdf.org/
Generic HTTP
rdf:type A URIs for rules
http://www.inria.fr/wimmics/corese/rules/typeprop
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> @prefix sp: <http://spinrdf.org/sp#> .
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> @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#> .
CONSTRUCT {?this rdf:type ?B}
WHERE { _:b1 sp:varName "A"^^xsd:string .
?A rdfs:subClassOf ?B.
[] a sp:Construct ;
?this rdf:type ?A sp:templates ([ sp:object _:b2 ;
} sp:predicaterdf:type ;
sp:subject _:b3
]) ;
sp:text """PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
CONSTRUCT {
?this a ?B .
• Explanation for RDFS }
WHERE {
?A rdfs:subClassOf ?B .
– Type propagation ?this a ?A .
}"""^^xsd:string ;
– Property property propagation sp:where ([ sp:object _:b2 ;
sp:predicate rdfs:subClassOf ;
sp:subject _:b1
– subClassOf transitivity ] [ sp:object _:b1 ;
sp:predicaterdf:type ;
sp:subject _:b3
– subPropertyOf transitivity ]) .
– Domain inference _:b2 sp:varName "B"^^xsd:string .
_:b3 sp:varName "this"^^xsd:string .
– Range inference
15

17. • 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)
16

18. Related Work
• Laconic and precise justifications [Horridgeet
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 [McGuinneset 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.
17

19. • 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.
18

20. 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
19

21. 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.
20

22. 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
21

23. • Summarization of justifications
Rules for finding components in the graphs of justification graphs
22

24. • 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
23

25. Thank You
Ratio4TA http://ns.inria.fr/ratio4ta/v1/
http://kolflow.univ-nantes.fr/
http://wimmics.inria.fr/
24