Southampton and The Open University. Preface(30)

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

Unfortunately,whenwestartedworktheoriginalSWRLproposalwaslim-

itedinthatfullyquanti edconstraintscouldnotbeexpressed6,thereforewe

electedtoextendSWRLwithourConstraintInterchangeFormat[4](CIF)in

ordertoachievethis.TheCIFrepresentationisbasedonrangerestrictedFirst

OrderLogic(FOL),andhasevolvedtouseRDF(S).CIFconstraintsaretrans-

formableforusewithavarietyofconstraintlogicprogrammingsolvers,including

CHIP,ECLiPSe,andtheSICStusPrologFDlibrary[5].TheAWBusescon-

straintsde nedbytheusertocontroltheconstructionoftheworkgroup.The

followingexampleshowshowaconstraintcanbeexpressedusingCIF/SWRL

[5]anddrawsuponthepreviouslyspeci edhasBaseLocnproperty:“Anywork-

groupcontainingatleast vemembersmustcontainatleasttwoindividualsfrom

di eringsites(baselocations).”Thiscanbewrittenas:

( g∈Workgroup)hasSize(g,s)∧greaterThanOrEqual(s,5)

( p1,p2∈Person)hasMember(g,p1)∧hasMember(g,p2)∧

hasBaseLocn(p1,b1)∧hasBaseLocn(p2,b2)∧

notEqual(p1,p2)∧notEqual(b1,b2)

Furtherexamples,inRDFsyntax,aregivenin[5].

TheAWBusestheSICStusPrologFDConstraintLibrary7intheCSPsolv-

ingandthereforemakesaclosedworldassumption(withnegation-as-failure).In

theCSPconstructionwearee ectivelyadoptinga‘bestinformationathand’

approach,forexample,ifwehadtheconstraint“aworkgroupmustnotcontain

anyonewhoisalecturer”thenthesetofvalid(non-lecturer)candidateswould

becompiledbasedonthedi erencewiththesetofknownlecturers.Whilethis

mightseemcontradictorytotheopenworldassumptionoftheSWingeneral,

wehavefoundthatthisstilldeliversvalidresultsinpractice.

6Discussion&Conclusion

Initspresentform,theAWBprovidesademonstrationofapracticalSW

problem-solvingsystemthatusesamixofreasoningmethodsoninstancedata:

ontologicalentailment,derivationrules,and nitedomainconstraintsolving.

WebelievethatinthisrespecttheAWBrepresentsanovelcontribution.This

sectionhighlightslessonslearnedfromtheAWBworktodate.

Pragmaticissuesofdatagathering,computationalcostofreasoning,anddata

qualityleadustopre-cachetheinstancedataonwhichtheAWBwouldoperate.

Whilethiscachingmodelisfarfromideal,weareabletotakeadvantageofthe

factthatreasoningistimeconsumingbyusingderivationrulestopre-generate

entailments(viaforwardchaining)withoutanyrealimpactontheuser.Since

thisisperformedpriortotheAWBuseraccessingthecacheandspecifyingthe

6TheSWRL-FOLW3CMemberSubmissionintroducesquanti ersbutisstillunder

discussionand,moreover,thelackofRDFsyntaxmakesitunsuitableforusebyusat

thisstage.See:/Submission/2005/SUBM-SWRL-FOL-20050411/7http://www.sics.se/isl/sicstus/

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(30)全文阅读和word下载服务。