entity-relationship extraction from wikipedia unstructured text - overview
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Entity-RelationshipExtractionfromWikipediaUnstructuredText
RadityoEkoPrasojo (Rido)PhDStudent@KRDB,FreeUniversityofBozen-Bolzano
Supervisedby:Mouna Kacimi &WernerNutt
20.07.16,Bilbao,Spain
Automaticallygenerated Manuallycurated
Automatedextractionwithout(yet)aKBasaresult
KnowledgeVault[1]
KnowledgeGraph
NELL[2]
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Infobox completion [3][4]
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WherewasObamaborn?
WhoarethechildrenofObama?
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WhenwasObamaborn?
WhoarethechildrenofObama?
Yeswecan!
Honolulu, HawaiiMaliaandSashaObama
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WhichareObama’sfavourite sportsteam?
DoesObamahavepets?
OurgoalistoenrichexistingKnowledgeBasesbyextractingnewfactsintheformofmachine-readableentity-relationshipfromWikipediaunstructuredtext.
Specificfocus:RDF
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Whyisitdifficult?
• Theextractionproblem• Entityextraction&disambiguation• Relationextraction
• Therepresentationproblem• Lackofpredefinedschema/ontology• Topic-independency• Complexfactrepresentation
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Whyisitdifficult?Example
• “Obamaisasupporterofthe ChicagoWhiteSox”• Straightforward,singletoninformation• Puresyntacticextractionpossible• Barack_Obama supporterOf Chicago_White_Sox
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Whyisitdifficult?Example
• “Obamaisasupporterofthe ChicagoWhiteSox”• Straightforward,singletoninformation• Puresyntacticextractionpossible• Barack_Obama supporterOf Chicago_White_Sox
• “He isalsoprimarily a ChicagoBears footballfaninthe NFL,butinhischildhoodandadolescencewas a fanofthePittsburghSteelers”• Complex,multipleinformation• Semanticunderstandingnecessary• …howdowerepresentthis?
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Example:representingcomplexfact
• “He isalsoprimarily a ChicagoBears footballfaninthe NFL,butinhischildhoodandadolescencewas a fanofthePittsburghSteelers”• Barack_Obama footballFan Chicago_Bears in NFL• supporterOf vsfootballFan• IsitnecessarytoincludeNFL inthewholerelations?• Whatabouttheadjectiveprimarily?Whatinformationdoesitimply?
• Barack_Obama fanOf Pittsburgh_Steelers• fanOf vs supporterOf• Missingthetimeinformationreferredin“inhischildhoodandadolescencewas”
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Approach
• Documentpreprocessingtoannotateallentityoccurences.• Grammaticaldependencytoextract(candidate)relations.
• Separationbetweentheextractionproblemandtherepresentationproblem• Wefirstextractallcandidaterelationsandthenlaterapplysemanticrefinementforbetterrepresentation.
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Preliminaryresults
• Groundtruthmanuallycuratedfrom25Wikipediaarticlesoffamouspeople.• Preprocessing• 4handcraftedextractionrulesleveraginggrammaticaldependency
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Ongoingwork• Automatedrulemining• Semanticrefinementforknowledgerepresentation• Ontologybuilding
• Namingandtaxonomyofentities,classes,andrelations• Handlingcomplexfact
• Obamaappointsxasyinz• Handlingmodality,adjectives,andsentiment
• “Inthepast”,“itisrumoured that”,“itisnottruethat”
• Futureevaluation• Biggergroundtruth(amount+topiccoverage)• EvaluatehowwellweenrichexistingKBs
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Futurework
• Metadataextraction• Dataquality,datacompleteness
• NaturallanguagequestionansweringbasedontheenrichedKB.
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