机器翻译概述

[e-mail](FAHQMT)„ŠŠŠ„ŠŠ„2090„(wordforwordtranslation)„„„Howareyou??Howoldareyou??(interlinguaapproach)„(interlingua)-(syntactic-semanticexpression)„„„„DLTEsperanto„n(n-1)2n„(transferapproach)„„„„„„(knowledge-basedmachinetranslation)„2070„„(worldknowledge)„(ontology)„2080„„„„„(rationalism)(empiricism)„(informationdissemination)ŠŠ„(informationassimilation)ŠŠ„„„(post-edit)„(translationmemory)„„„„„(1)(2)(3)(CrossLanguageInformationRetrieval)(4)语标语词语语句译词选择态结转换词规则库切标句结转换结调译词选择Sheputsabunchofflowersontable.ExampleBasedMachineTranslation(EBMT)1984„„„„„„EBMT„Š„Š„„Therabbiteatsvegetables„Sulfuricacideatsmetal„Heeatsapple?EBMT„„Š„„„Statistic-BasedMachineTranslation(SBMT)50Chomsky90„„„)|Pr(argmaxˆSTTT=)Pr()|Pr()Pr()|Pr(STSTST=TS)|Pr()Pr(argmaxˆTSTTT=Pr(S|T)称为语ST译Pr(T)称为语T语„Šnn-gram„„ŠIBM(EM—)∏∏∏==⋅⎟⎟⎠⎞⎜⎜⎝⎛⋅=niljifijijiiljitstfTS1,,1),|Pr()|Pr()|Pr()|Pr()|Pr(iitftifi),|Pr(ljilij)|Pr(ijtstisj:Theproposalwillnotnowbeimplemented:Les(1)propositions(2)ne(4)seront(3)pas(4)mises(7)en(7)application(7)maintenant(5)Marianodabaunabofetadaalabrujaverde(Spanish)(exhaustivesearch)(pruningstrategy)100%2090„()„„“”„„„RBMT„„()()„ŠBrown(1991)ŠGale(1993)„ŠKay(1993)90%„„S=s1s2…sJT=t1t2…tIA},...,{},...,,{2121IJtttsssA×⊆}},...2,1{},,...,2,1{|),{(IiJjijA∈∈⊆t0A{1,2,…,J}{0,1,2,…,I}aj=A(j)A=a1a2…aJ„„„„Š„Š-JI1)2)P(S,A|T)3)P(S,A|T)AP(S,A|T)?EMGIZA++1234„“”„ALPACŠ(Intelligibility)Š(Fidelity)„(Mu)1234567„„n-gram(BLEU)1949WarrenWeaverMT„(decoding)1954Georgetown50Bar-HillelMT„“”(semanticbarrier)60ALPACMT„(Intelligibility)„(Fidelity)70„TAUM-METEO„SYSTRAN„80„ODA„Eurotra„MT„90