Southampton and The Open University. Preface(27)

Advanced Knowledge Technologies is recognised as a leading research programme conducted at some of the foremost informatics departments in Britain. It is also a training ground for a new generation of researchers. To highlight the work of these students, a

ThedatacontainedwithintherepositorywasscrapedfromHTMLpages

withotherinformationbeinghandcraftedRDF.Thishasresultedinthecon-

tentoftherepositorybeingincompleteandcontainingerrors,contradictionsand

duplications.Thesheerscaleoftheamasseddatacausesprovenanceandtrust

issuesthataretangentialtoourcurrentscopeofwork,meaningwerequireda

‘tidy’datasetbasedontheexistinginformation.Inourearlyexperimentsthe

sheervolumeofdata(10M+triples)alsoimpededourprogress–duemainlyto

thereasoningtime.Therefore,asastartingpointweusedasubsetofcleaned-up

datathatwasmanageable,yetstillrealistic,andalsoensuredtractablereason-

ing.ThissetonlycoverstheindividualsinvolvedintheAdvancedKnowledge

Technologies(AKT)project.

This‘sandbox’enabledustomakeseveralassumptionsabouttheenviron-

mentweareworkinginandfocusprimarilyontheinterplaybetweenrules,

constraintsandinstancebasedreasoningratherthan re- ghtingdataand/or

ontologicalreconciliationissues.Ontologicalreasoninginvolvesgeneratingnew

factsbaseduponthepropertiesandclasshierarchywithintheontology.There-

fore,weassumethattheunderlyingontologyisconsistentandwellformedand

thattheassociatedinstancedataisvalid(i.e.doesnotcontaincontradictions)

andanyequivalencesareexplicitlystated.

Inbuildingthecache,wee ectivelypre-computeallRDF(S)typesbasedon

thefactsandassertedruleswehave(becauseOWLLiteisdecidable)andthe

derivationrulesassert‘safe’factualinformation.Webelievethatthisispossible

becauseweonlyhavea nitedomainofinstancedata.

4DerivationRules

Althoughareasonercanderiveadditionalontologicalentailments,basedupon

propertyandclasshierarchies,sometimesitisnecessarytoinferpertinentin-

formationthatcannotbedeterminedotherwise–hencetheneedforderivation

rules.

SWRLisusedtostatetheserules,sinceitisbaseduponOWLLiteandDL

andthereforehasclosetiestotheunderlyingontology.ItallowsHornclausesto

beassertedaboutthesemanticdatatocreateimplicationswhichweusetoen-

codeourderivationrules(makingthemavailablealongwiththedata).Weutilise

thesetocreatenewfactsbasedontheinstancedata.Forexample,considerthe

followingrule,usedtodeterminethehasBaseLocnproperty:“Ifapersonhas

ana liationwithauniversityandthatuniversityhasapostaladdressofacity,

thenthisimpliesthatthepersonhasabaselocationofthesamecitywherethe

universityislocated.”IninformalSWRLsyntax,where?xdenotesavariable,

thiscanbewrittenas:

Person(?p)∧University(?u)∧hasAffiliation(?p,?u)∧

hasAddress(?u,?c)∧City(?c) hasBaseLocn(?p,?c)

IntheAWBwehavetheoptionofadoptingtwodi erentapproachestogener-

搜索“diyifanwen.net”或“第一范文网”即可找到本站免费阅读全部范文。收藏本站方便下次阅读，第一范文网，提供最新人文社科Southampton and The Open University. Preface(27)全文阅读和word下载服务。