The Use of NLP Techniques in CLIR

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1、TheUseofNLPTechniquesinCLIRBarbelRipplingerIAIMartin-Luther-Str.1466111Saarbrucken,Germanybabs@iai.uni-sb.deAbstractTheapplicationofnlptechniquestoimprovetheresultsofinformationretrievalisstillconsideredasacontroversialissue,whereasnlptechniquesincross-languageinformationre-t

2、rieval(clir)arealreadywellestablished,atleastforthetranslationpart.Inthispaper,theclircomponent-Mpro-IR-isrepresentedwhichhasbeendevelopedasthecoremod-uleofamultilingualinformationsysteminalegaldomain.Thiscomponentusesnotonlythelexicalbaseformforindexingbut,inadditionderivati

3、onalinformationandforGermaninformationaboutthedecompositionofcompounds.Thisinformationisprovidedbyaso-phisticatedmorpho-syntacticanalyser(mpro)andisexploitednotonlyforquerytranslationbutalsoforqueryexpansionaswellasthesearchandthedocumentranking.Mpro-IRisdevelopedforadomainwi

4、thafocusonrecall.Theobjectiveoftheclefevaluationwastoassessthislinguisticbasedretrievalapproachinanunrestricteddomain.Thefocusoftheinvestigationwasonhowderivationanddecompositioncancontributetoimprovetherecall.Duetotimerestrictionwecouldonlysubmitonecross-languagerunwithEngli

5、shasquerylanguageusingthephrasesearchcomponentofMpro-IRwhichisrestrictedtosearchonlyforonetranslation,andwherethequeriedtermshavetooccurinthesamesentence.Theserestrictionsresultinasmallnumberofretrieveddocuments,andthusinalowperformance.1IntroductionTheMpro-IRsystemisaclirsys

6、tembasedonquerytranslationandfocusesratheronabetterrecallthanonabalancedrecallandprecision.Toimprovetherecall,thesystemtriestotakeadvantageofasophisticatedlinguisticprocessingcomponentwhoseresultsareusedinthemono-lingualretrievalmodules.Basedontheoutputofamorpho-syntacticanal

7、ysiswhichprovidesthefullrangeofmorphologicalinformation,notonlyin ectionwhichwouldcorrespondtothepowerofastemmer(Porterstemmer)butalsoderviationalanddecompositionofcompoundnounsisexploited.Thisinformationisusedfortheindexing,queryexpansion,searchanddocumentrank-ing.Thetransla

8、tioncomponenttakesadvantageoftheprovidedpart-of-speechaswellasofthes