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1、TrainingConditionalRandomFieldsusingVirtualEvidenceBoostingLinLiaoTanzeemChoudhury?DieterFoxHenryKautzUniversityofWashington?IntelResearchDepartmentofComputerScience&Engineering1100NE45thSt.Seattle,WA98195Seattle,WA98105Abstracteraldomains.However,nogeneralguidancehasbeengivenonwhenMPL
2、canbesafelyused,andindeedMPLhasbeenWhileconditionalrandom?elds(CRFs)havebeenobservedtoover-estimatethedependencyparametersinsomeappliedsuccessfullyinavarietyofdomains,theirexperiments[GeyerandThompson,1992].trainingremainsachallengingtask.Inthispaper,Inaddition,neitherMLnorMPLperformsf
3、eatureselec-weintroduceanoveltrainingmethodforCRFs,tionexplicitly,andneitherofthemisabletoadequatelyhan-calledvirtualevidenceboosting,whichsimulta-dlecontinuousobservations.Theselimitationsmakethemneouslyperformsfeatureselectionandparameterunsuitableforsometasks,suchasactivityrecogniti
4、onbasedestimation.Toachievethis,weextendstandardonrealsensordataandidentifyingthesetoffeaturesthatboostingtohandlevirtualevidence,whereanob-aremostusefulforclassi?cation.Alternatively,boostinghasservationcanbespeci?edasadistributionratherbeensuccessfullyusedforfeatureselectioninthecont
5、extofthanasinglenumber.Thisextensionallowsustoclassi?cationproblems[ViolaandJones,2002].However,itsdevelopauni?edframeworkforlearningbothlocalapplicationtorelationaldataremainsanunsolvedproblemandcompatibilityfeaturesinCRFs.Inexperimentssinceitassumestheindependenceofhiddenlabels.onsyn
6、theticdataaswellasrealactivityclassi?-Inthispaper,weshowhowtoseamlesslyintegrateboost-cationproblems,ournewtrainingalgorithmout-ingandCRFtraining,therebycombiningthecapabilitiesofperformsothertrainingapproachesincludingmax-bothparadigms.Theintegrationisachievedbycuttingaimumlikelihood,
7、maximumpseudo-likelihood,andCRFintoindividualpatches,asdoneinMPL,andusingthesethemostrecentboostedrandom?elds.patchesastraininginstancesforboosting.ThekeydifferencetoMPL,however,isthatinourframeworktheneighborlabels1Introductionarenottreatedasobserved,butasvirtualevidencesorbeliefs.T