Computers - Information Retrieval

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1、INFORMATIONRETRIEVALC.J.vanRIJSBERGENB.Sc.,Ph.D.,M.B.C.S.DepartmentofComputingScienceUniversityofGlasgowPREFACETOTHESECONDEDITIONThemajorchangeinthesecondeditionofthisbookistheadditionofanewchapteronprobabilisticretrieval.ThischapterhasbeenincludedbecauseIthinkthisisoneofthemostinterestingandactiv

2、eareasofresearchininformationretrieval.TherearestillmanyproblemstobesolvedsoIhopethatthisparticularchapterwillbeofsomehelptothosewhowanttoadvancethestateofknowledgeinthisarea.Alltheotherchaptershavebeenupdatedbyincludingsomeofthemorerecentworkonthetopicscovered.InpreparingthisneweditionIhavebenefi

3、tedfromdiscussionswithBruceCroft,DavidHarper,StephenRobertsonandKarenSparckJones.IamgratefultotheUniversityofCambridgeComputerLaboratoryforprovidingmewiththefacilitiesforcarryingoutthework.Finally,IamindebtedtotheRoyalSocietyforsupportingmeontheirScientificInformationResearchFellowship.PREFACETOTH

4、EFIRSTEDITIONThematerialofthisbookisaimedatadvancedundergraduateinformation(orcomputer)sciencestudents,postgraduatelibrarysciencestudents,andresearchworkersinthefieldofIR.Someofthechapters,particularlyChapter6*,makesimpleuseofalittleadvancedmathematics.However,thenecessarymathematicaltoolscanbeeas

5、ilymasteredfromnumerousmathematicaltextsthatnowexistand,inanycase,referenceshavebeengivenwherethemathematicsoccur.Ihadtofacetheproblemofbalancingclarityofexpositionwithdensityofreferences.Iwastemptedtogivelargenumbersofreferencesbutwasafraidtheywouldhavedestroyedthecontinuityofthetext.Ihavetriedto

6、steeramiddlecourseandnotcompetewiththeAnnualReviewofInformationScienceandTechnology.*ThisisChapter7inthesecondedition.Normallyoneisencouragedtociteonlyworksthathavebeenpublishedinsomereadilyaccessibleform,suchasabookorperiodical.Unfortunately,muchoftheinterestingworkinIRiscontainedintechnicalrepor

7、tsandPh.D.theses.Forexample,mosttheworkdoneontheSMARTsystematCornellisavailableonlyinreports.LuckilymanyofthesearenowavailablethroughtheNationalTechnicalInformationService(U.S.)andUniversityMicrofilms(U.K.).Ihave