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OWL Instance Data Evaluation

Li Ding, Jiao Tao, and Deborah L. McGuinness

Tetherless World ConstellationComputer Science Department

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Motivation

• Focus of this talk– OWL instance data

• Why is it interesting?– Instance data dwarfs class data on the web– Instance data may be published independently from

class and property descriptions and may cause unexpected issues

– Instance data is often used by many applications, some of which may not be aware of the class and property descriptions

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A new ontology A new instance data

Wine ontology

Semantic Inconsistencyin Distributed Publishing

wine:EarlyHarvest wine:LateHarvest

wine:Wine

rdfs:subClassOf rdfs:subClassOf

owl:disjointWith

wine:BadWineDefinition

rdfs:subClassOf rdfs:subClassOf

wi:BadWineInstance

rdf:type rdf:type

Case1: semantic inconsistencycaused by a new class.

Case2: semantic inconsistencycaused by a new instance.

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Limited Scope of Data

Instance data A Instance Data B

Wine ontology

wine:Zinfandel

wine:Wine

rdfs:subClassOf

wi:W1wi:W1

rdf:typerdf:type

• Consider Instance data A, application may need additional instance data to meet cardinality requirement

Surfing via namespace of wine ontology

wine:hasMaker

owl:Restriction

"1"^xsd:nonNegativeInteger

rdfs:subClassOfowl:onProperty

owl:cardinality

wi:WineMaker1

wine:hasMaker

wine:Red

wine:hasColor

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Issues with OWL instance data• General Issues

– RDF syntax– OWL DL semantic consistency

• Issues related to an individual’s type description: – Unexpected individual type: (rdfs:domain, rdfs:range,

owl:allValuesFrom)– Redundant individual type– Non-specific individual type

• Issues related to property restrictions: – Unexpected individual type: (owl:hasValue)– Missing property value (owl:minCardinality, owl:cardinality)– Excessive property value (owl:maxCardinality, owl:cardinality)

• (Customizable and Extensible) Issues related to style: – Naming conventions– Missing annotations,…

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Implementation

• Load instance data - (D)– Is D syntactically correct?

• Load the corresponding ontologies - (O={O1,O2,…})– Is any Oi inaccessible?

• Derive the inferred model, - Inf(D+O)– Is D semantically consistent with O?

• Use Pellet OWL DL reasoner

• Check style issues– Is more explicit description about the instance needed?

• Run Sparql on (D) and Inf( D+O )– query D to confirm the issue is caused by D– query Inf(D+O) to check presence of issue

– Is there any redundancy or ambiguity in D?

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Wine Ontology (Partial)Class(a:Wine partial restriction(a:hasSugar cardinality(1)) restriction(a:madeFromGrape minCardinality(1)) restriction(a:hasBody cardinality(1)) restriction(a:hasColor cardinality(1)) restriction(a:hasFlavor cardinality(1)) restriction(a:hasMaker cardinality(1)) restriction(a:locatedIn someValuesFrom(a:Region)) restriction(a:hasMaker allValuesFrom(a:Winery)))

Class(a:Zinfandel complete intersectionOf(restriction(a:madeFromGrape value (a:ZinfandelGrape)) a:Wine restriction(a:madeFromGrape maxCardinality(1))))

Class(a:Zinfandel partial restriction(a:hasSugar value (a:Dry)) restriction(a:hasFlavor allValuesFrom(oneOf(a:Moderate a:Strong))) restriction(a:hasBody allValuesFrom(oneOf(a:Medium a:Full))) restriction(a:hasColor value (a:Red)))

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An Example SPARQL Query forMissing Property Value

1. PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>2. PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>3. PREFIX owl: <http://www.w3.org/2002/07/owl#>4. SELECT ?i ?p ?c5. FROM NAMED <http://tw.rpi.edu/2008/03/wine-instance.owl>6. WHERE { { ?c rdfs:subClassOf ?r.7. ?r rdf:type owl:Restriction .8. ?r owl:onProperty ?p .9. ?r owl:cardinality ?card .10. FILTER( ?card = 1 ) 11. OPTIONAL { ?i ?p ?o . }12. "FILTER( !BOUND(?o) ) }13. GRAPH <http://tw.rpi.edu/2008/03/wine-instance.owl>14. { ?i rdf:type ?c . } }

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Conclusion

• Current work– identified OWL instance data evaluation

problem– Listed several common issues in OWL

instance data– used SPARQL + Inference to clarify issue

definition and simplify issue detection

• Future work– Use SPARQL-DL API

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Questions?or

More Slides?

The 7th International Semantic Web ConferenceISWC 2008 • Karlsruhe DE • 26-30 October 2008

http://iswc2008.semanticweb.org/

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A Questionnaire for OWL User Experiences

• OWL constructs– What have been used?– What are still missing?

• OWL inference– What inference has been used to solve problem? – What other inference is used together with OWL

 inference, e.g. sparql, swrl?• OWL user experience

– How hard is it to build/reuse OWL ontology– How hard is it to build/reuse OWL instance data– How OWL help web users?

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OWL Instance Data Evaluation Architecture

semantic web data evaluation services

RDF parsing and validationRDF parsing and validation

referenced ontology resolutionreferenced ontology resolution

OWL species classificationOWL species classification

RDFS/OWL semantics validationRDFS/OWL semantics validation

general style evaluationgeneral style evaluation

domain specific style evaluationdomain specific style evaluation

instance datainstance data

referenced ontologiesreferenced ontologies

URI or text of RDF document evaluation report

optionalontologiesoptional

ontologies