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123 Jiao Tao 1, Li Ding 2, Deborah L. McGuinness 3 Tetherless World Constellation Rensselaer...

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  • Jiao Tao1, Li Ding2, Deborah L. McGuinness3

    Tetherless World ConstellationRensselaer Polytechnic InstituteTroy, NY, USA

    1 PhD Student2 Postdoctoral Research Fellow3 Tetherless World Senior Constellation ProfessorInstance Data Evaluation for Semantic Web-Based Knowledge Management Systems

  • Semantic Web-based KMSThe Semantic Web is a next generation of the Web which formally defines the relations among terms with ontologies, gives well-defined meaning to information, and enables machines to comprehend the content on the Web (Berners-Lee, Hendler, & Lassila 2001).Semantic Web-based Knowledge Management Systems enable the next generation of KMSApplies semantic web technologies to improve on traditional knowledge-management approaches or realize emerging knowledge-services requirements (Davies, Lytras, & Sheth 2007)Schemas are represented as ontologies (O) and data is SW instance data (D)

  • Data Evaluation in SW-based KMS: State of the ArtIn SW-based KMS, instance data often accounts for orders of magnitude more data than ontology (Ding & Finin 2006).However most data evaluation work (Rocha et al. 1998) focuses on ontology evaluation, i.e., checking whether the ontologies correctly describe the domain of interest.There is very little, if any, work on evaluating the conformance between ontologies and instance data.

  • 1. Create KMS schemaas ontologies O(including embedded semantic expectations)

    WebOD3. Instantiate KMS ontologies4. Publish KMS instance data DO2. Acquire KMS ontologiesDo semantic expectations match between O and D?No syntax errors?Instance Data Evaluation in SW-based KMSSemantic expectation mismatches:(i) Logical inconsistencies(ii) Potential issues

  • Generic Evaluation Process (GEP)Load instance data DIs loading failing?Parse instance data DIs D syntactically correct?Load referenced ontologies O = {O1,O2, }Is Oi reachable? where Oi defines the terms used by D.Inspect logical inconsistencies in DIs Oi logically consistent?Merge all consistent referenced ontologies into O'Are D+O logically consistent? Inspect potential issues in DCompute DC = INF(D,O') which includes all triples in D and O', and all inferred sub-class/sub-property relationsIs there any potential issue in D?

  • Potential IssuesUnexpected Individual Type (UIT) Issuerdfs:domainrdfs:rangeowl:allValuesFromRedundant Individual Type (RIT) IssueNon-specific Individual Type (NSIT) IssueMissing Property Value (MPV) Issueowl:cardinalityowl:minCardinalityExcessive Property Value (EPV) Issueowl:cardinalityowl:maxCardinality

  • Graph Patterns of Potential IssuesExample: Missing Property Value IssueMake sure all instances of wine have a Maker specified

  • SPARQL Solutions forPotential Issue DetectionExample: MPV Issue

  • Implementation and EvaluationDemo: TW OIE Service http://onto.rpi.edu/demo/oie/Comparative experiment results

  • Status, Current and Future WorkTW OIE implemented and Service provided as part of the Inference Web Explanation Framework (IW McGuinness and Pinheiro da Silva, 2004)Ongoing work: characterize and detect potential (integrity) issues in instance dataAn Initial Investigation on Evaluating Semantic Web Instance Data (WWW 2008)Characterizing and Detecting Integrity Issues in OWL Instance Data (OWLED2008 EU) Integrity Constraint Modeling and Checking for Semantic Web Data An Answer Set Programming-based Approach (submitted to ESWC 2009)Future work:Formal representation for expressive integrity constraintsAutomatic updates to data to fix problemsEnhanced explanation capabilities

  • ReferencesT. Berners-Lee, J. Hendler, and O. Lassila, The Semantic Web: A New Form of Web Content that Is Meaningful to Computers Will Unleash a Revolution of New Possibilities, Scientific American, pp. 3443, 2001. J. Davies, M. Lytras, and A. Sheth, Semantic-Web-Based Knowledge Management, IEEE Internet Computing, Vol. 11, No. 5, pp. 14-6, 2007.L. Ding, and T. Finin, Characterizing the Semantic Web on the Web, ISWC, pp. 242-257, 2006.R. A. Rocha, S. M. Huff, P. J. Haug, D. A. Evans, and B. E. Bray, Evaluation of a Semantic Data Model for Chest Radiology: Application of a New Methodology, Methods of Information in Medicine, Vol. 37, No.4-5, pp. 477-490, 1998.D. L. McGuinness and P. Pinheiro da Silva. Explaining Answers from the Semantic Web: The Inference Web Approach. Journal of Web Semantics. Vol.1 No.4., pp 397-413, 2004.

  • Extras

  • Semantic e-Science Data Evaluation

  • *WWWToolkit

    Proof Markup Language (PML)

    LearnersJTP/CWMSPARKUIMAIW Explainer/AbstractorIWBaseIWBrowserIWSearchTrustJustificationProvenance*KIF/N3SPARK-LText AnalyticsIWTrustprovenanceregistrationsearch enginebased publishingExpert friendlyVisualizationEnd-user friendly visualizationTrust computationOWL-S/BPELSDSTrace of web service discoveryLearning ConclusionsTrace of task execution Trace of information extractionTheorem prover/RulesInference Web Explanation ArchitectureSemantic Web based infrastructurePML is an explanation interlingua Represent knowledge provenance (who, where, when)Represent justifications and workflow traces across system boundariesInference Web provides a toolkit for data management and visualization

  • McGuinness Microsoft eScience December 8, 2008*Global ViewExplanation as a graphCustomizable browser optionsProof styleSentence formatLens magnitudeLens width

    More informationProvenance metadataSource PMLProof statisticsVariable bindingsLink to tabulatorViews of ExplanationExplanation (in PML)filteredfocusedglobalabstractiondiscourseprovenancetrust

  • McGuinness Microsoft eScience December 8, 2008*Provenance ViewSource metadata: name, description, Source-Usage metadata: which fragment of a source has been used whenViews of ExplanationExplanation (in PML)filteredfocusedglobalabstractiondiscourseprovenancetrust

  • LinksTetherless World Instance Ontology Instance Evaluator: http://onto.rpi.edu/demo/oie/ Inference Web inference-web.org Semantic eScience class link (with book to follow) http://tw.rpi.edu/wiki/Semantic_e-Science

  • McGuinnessNSF/NCAR May 6, 2008*

    *******Each wine instance is expected to have a value for property hasMaker due to the owl:cardinality restriction in wine ontology. However, in the instance data, W has no maker.*In D, individual i is declared to be of type c. In DC, c is a subclass of restriction r which requires each instance of r to have n values for property p. Since, in DC, i is not found to have a value for property p, i has MPV issue.Note: To detect general MPV issues, one SPARQL query is not enough. For conciseness, we use above SPARQL query which can sucessfully detect MPV issues in OWL-Lite instance data since cardinality restrictions are limited to value 0 or 1 in OWL-Lite.

    *Tools: Pellet, WonderWeb species validator (WW), BBN validator (BBN), ODEval, ConsVisor.

    Test Files and associated issues: D1 - No RDF triples D2 - RDF triples with syntax errors D3' - Plain literal missing data type D4' - Cardinality violation D5' - Inconsistent individual type D6' - Unexpected individual type D7' - Redundant individual type D8' - Non-specific individual type D9' - Missing property value D10' - Excessive property valueTo make up the effect of incomplete referenced ontologies loading of other tools, for each test file Di, we preload all of its referenced ontologies O, then merge O with Di into new file Di', which is used as the actual input data for test. Since syntax error detection does not require loading reference ontologies, we do not change the original test files.

    Notation: Y: the tool can correctly detect the error/issue. N: the tool can not detect the error/issue. PE: exceptions happened in evaluation.

    Analysis:TW OIE successfully detects all of the issues in the test filesOnly Pellet can find the semantic inconsistenciesIf Pellet had used its own referenced ontology loading strategy, it would not have beenable to detect the cardinality violation and inconsistent individual type issues.***Each wine instance is expected to have a value for property hasMaker due to the owl:cardinality restriction in wine ontology. However, in the instance data, W has no maker.****Explanation as a graphCustomizable browser options proof style , sentence format, lens magnitude, lens width More information, provenance metadata, source PML, proof statistics**Each wine instance is expected to have a value for property hasMaker due to the owl:cardinality restriction in wine ontology. However, in the instance data, W has no maker.*

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