自然語(yǔ)言理解-形式化句法理論

形式化語(yǔ)法理論

GrammarFormalism上海交通大學(xué)陳玉泉內(nèi)容提要概述（語(yǔ)法和語(yǔ)言）喬姆斯基（Chomsky）語(yǔ)法理論基于合一（Unification）的語(yǔ)法理論其它一些的語(yǔ)法理論（不基于上下文無(wú)關(guān)文法）一、概述什么是語(yǔ)法？AmathematicsystemDefinealanguageGivesyntax(structure)toasentence(string)人工語(yǔ)言及其語(yǔ)法基于符號(hào)無(wú)歧義或簡(jiǎn)單歧義高效從可計(jì)算角度分類0,1,2,3UnrestrictedGrammarTuringMachine？ContextSensitiveGrammarTuringMachine？ContextFreeGrammarPushdownAutomatonO(n3)RegularExpressionFiniteStateAutomatonO(n)自然語(yǔ)言及其語(yǔ)法復(fù)雜歧義多樣形式化語(yǔ)法理論的目標(biāo)判斷一句句子是否合法給出該句子唯一合法的結(jié)構(gòu)給出該句子中各成分（詞）之間的關(guān)系形式化語(yǔ)法理論應(yīng)具備的特性linguisticallyadequate準(zhǔn)確描述自然語(yǔ)言expressive對(duì)語(yǔ)言世界用數(shù)學(xué)方法描述computationaleffective可計(jì)算，并且高效主要流派喬姆斯基語(yǔ)法理論基于合一的語(yǔ)法理論其它（不基于上下文無(wú)關(guān)文法）二、喬姆斯基語(yǔ)法理論NoamChomskyAmericanlinguist,writer,teacher,andpoliticalactivistPublicationsSyntacticStructuresAspectsoftheTheoryofSyntaxAmericanPowerandtheNewMandarins

PeaceintheMiddleEast

LecturesonGovernmentandBindingTheFatefulTriangle

DeterringDemocracyTheMinimalistProgram發(fā)展過(guò)程轉(zhuǎn)換生成語(yǔ)法（1957）SyntacticStructure.TheHague:Moutong&Co.管轄與約束理論（1981）LecturesonGovernmentandBinding.Foris,Dordrecht最簡(jiǎn)方案（1992）AMinimalistProgramforLinguisticsTheory,MITOccasionalPapersinLinguistics,#1GB之前SurfaceStructureDeepStructureRules&LexiconTransfor-mationsSemanticInterpretationUtteranceGB之后SurfaceStructureDeepStructureRules&LexiconLogicalFormPhonologicalFormmoveaX-Bar-SyntaxSubcategorizationSelectionalRestrictionsCaseTheoryq-CriterionBindingPrinciple短語(yǔ)結(jié)構(gòu)phrasalstructure句子的結(jié)構(gòu)是層次化的（hierarchical）Tree范疇（Category）Commoncategorialmembershipisevidencedbyintersubstitutivity中心詞（Headofaphrase）決定短語(yǔ)行為的詞Recursive某個(gè)類型可以包含在它自身中IntersubsitutivityandheadLondon,thewoman,theoldman,theproudyoungchild ------isknowntometheproudyoungchildtheproudchildtheyoungchild------childistheheadX-Bar理論VP?<leftarguments>V<rightarguments>VPVNP VPADVVPVPPX-BarX2

?<specifier>X1X1

?X0<complements>N的complements是形容詞，specifier是冠詞V的complements是賓語(yǔ)，specifier是主語(yǔ)這樣，V0表示單個(gè)動(dòng)詞，V1表示動(dòng)詞結(jié)構(gòu)，V2表示句子01,12X-Bar理論（cont.）V1V1V0likeshisvisitthisweekinShanghaiN2N2P2V1題元理論q-Criterion題元理論研究各詞項(xiàng)之間的題元關(guān)系，即傳統(tǒng)語(yǔ)，即傳統(tǒng)語(yǔ)法中用施事、受事、工具等術(shù)語(yǔ)表示的概念范疇題元理論以動(dòng)詞為中心，認(rèn)為每一個(gè)題元角色都是由動(dòng)詞分配的。agent:johnreadsabookinstrument:thekeyopensthedoorlocation:thebookcontainsgoodideas句中的每一個(gè)成分都必須有一個(gè)題元角色（coherence），同時(shí)，中心動(dòng)詞的所有題元角色都已被分配（completeness）。格理論（CaseTheory）與語(yǔ)言相關(guān)。一般地，動(dòng)詞，介詞賦格，名詞N2接受格X0

向N2賦格管轄GovernmentC-Command:ac-commandsb(a

1

b)iffeverybranchingnodeg,whichdominatesa,alsodominatesbadoesnotdominatebExample:Yc-commandsZ,C,D,EZc-commandsA,BAc-commandsBBc-commandsACc-commandsD,EXEDCBAZY管轄GovernmentM-Command:xm-commandyiffneitherofxandydominatestheother,andeverymaximalprojectionthatdominatesxalsodominatesy.N0dosenotc-commandsDetbutm-commandsDetXN0N1DetBAN2Y管轄GovernmentGovernment:xgovernsyiffx=X0xm-commandsy,andifex.zm-commandsy,zm-commandxorym-commandz.Headalwaysgoverntheircomplementsandspecifiers.動(dòng)詞管轄主語(yǔ)和賓語(yǔ)，但主語(yǔ)不管轄賓語(yǔ)約束理論BindingPrinciple解決問(wèn)題：指稱關(guān)系CompleteFunctionalComplex(CFC):AconstituentaisaCFC,ifitiscompleteandcoherent(q-criterion)原則照應(yīng)詞在CFC內(nèi)受約束，即它的先行詞必定在CFC內(nèi)。代名詞在CFC內(nèi)是自由的。指稱詞總是自由的。其中，照應(yīng)詞：包括反身代詞myself，yourself，相互代詞eachother等。代名詞：指?jìng)鹘y(tǒng)語(yǔ)法中的人稱代詞，如he,him等。指稱詞：就是通常所說(shuō)的名詞短語(yǔ)，如theman，john等。約束理論BindingPrincipleJohnwantsTomtocriticizehimself.himself只能是Tom，不可能是John原則一JohnwantsTomtocriticizehim.him不能是Tom，但可能是John原則二TransformationSentenceWhatdidyougivetoJohn?D-Structure:[?[you[Tense[givewhattoJohn]]]]S-Structure[Whati[do+Tensej[you[tj[giveti

[toJohn]]]]]]轉(zhuǎn)換類型Passivizationsurfacestructure: thebookisgiventolindabyjandeepstructure: jangivesthebooktolindaAgent-Deletionsurfacestructure: thebookisgiventolindadeepstructure: someonegivesthebooktolindaEqui-NP-Deletionsurfacestructure: janpromiseslindatocomedeepstructure: janpromiseslindathatjancomes轉(zhuǎn)換類型Raisingsurfacestructure: janseemstocomedeepstructure: (it)seemsthatjancomesAnaphorssurfacestructure: janiwasheshimselfideepstructure: janwashesjanQuestion-Formationsurfacestructure: whatdoesjanread?deepstructure: ?janreadswhatImperatives(Agent-Deletion)surfacestructure: givethetoytoherdeepstructure: somonegivesthetoytoher轉(zhuǎn)換動(dòng)作SubstitutionDisplaceandelementAdjunction…[Y…X…]…[YXi[Y…ti…]Example:[S[NPtheboy][VP[vbroke][NPthewindow]]]Theboybrokethewindow.Thewindowwasbroken(t)bytheboy.Movements:ReplacingsubjectNPbyobject;Postposingthesubjuct,addbyIntroducenewtense三、基于合一的語(yǔ)法基于合一的語(yǔ)法功能合一語(yǔ)法FUG廣義短語(yǔ)結(jié)構(gòu)語(yǔ)法GPSG中心詞驅(qū)動(dòng)短語(yǔ)結(jié)構(gòu)語(yǔ)法HPSG詞匯功能語(yǔ)法LFG共同特點(diǎn)：引入特征和特征的合一特征結(jié)構(gòu)特征：[屬性：值]特征結(jié)構(gòu)：特征的集合，其中任何兩個(gè)屬性不能相同一個(gè)特征結(jié)構(gòu)的例子：Num:pl|sgPer:3復(fù)雜特征集嵌套的特征結(jié)構(gòu)（nest），允許重入（reentrance）Cat:vSub:

Cat:rLex:heNum:sgCat:vPer:3(1)Sub:Cat:rPer:(1)Lex:he復(fù)雜特征集的圖形表示DAG3hervperpercatcatlexsub合一合一是定義在兩個(gè)特征結(jié)構(gòu)之間的一種操作合一成功：則原來(lái)的兩個(gè)獨(dú)立的特征結(jié)構(gòu)成為同一個(gè)特征結(jié)構(gòu)合一失?。翰划a(chǎn)生新的特征合一（cont）合一運(yùn)算可遞歸定義為:如果a、b都是原子值，若a和b相等，則a?b=a，否則a、b合一失敗如果a、b均為特征結(jié)構(gòu)，則對(duì)于a、b中的每一個(gè)特征f：若f(a)=v，但f(b)的值未經(jīng)定義，則<f,v>屬于a?b若f(b)=v，但f(a)的值未經(jīng)定義，則<f,v>屬于a?b若f(a)=v1，f(b)=v2，v1和v2相容，則<f,(v1∪v2)>屬于a?b，如果v1和v2不相容，則合一失敗*相容（consistent）針對(duì)兩個(gè)特征結(jié)構(gòu)而言，指存在另一個(gè)特征結(jié)構(gòu)，同時(shí)包含(subsume)這兩個(gè)結(jié)構(gòu):包含:D1

íD2

?

"f?dom(D1):f(D1)íf(D2) &("p,q?dom(D1)*:p(D1)=q(D1)?p(D2)=q(D2)合一的算法描述D1,D2andDareconsideredassetsD:={};

while(D1!={}){

D1:=D1/(f=v);

if(f?dom(D2)){

D2:=D2/(f=v‘);

D:=Dè{f=vèv‘};

}

elseD:=Dè{f=v};

}

D:=DèD2;合一的例子Cat:vNum:sgCat:vNum:sgPer:3Cat:vNum:sgPer:3合一的例子（cont）Cat:vNum:sgCat:vNum:plPer:3合一的特性交換率結(jié)合率LFG詞匯功能語(yǔ)法（LexicalFunctionalGrammar）RonaldM.Kaplan,JoanBresnan

LexicalFunctionalGrammar-AFormalSystemforGrammaticalRepresentation

in:JoanBresnan(ed.),TheMentalRepresenta-tionofGrammaticalRelations,MITPress,Cambridge(MA)1982表示層次LexicalStructureC-structure(ConstituentStructure)F-structure(FunctionalStructure)LexicalStructurethe:Det, (-spec)=def

(-per)=3man:N, (-pred)=man

(-per)=3

(-num)=sgreads:V, (-pred)=read(subj,obj)

(-subjper)=3

(-subjnum)=sga:Det, (-spec)=indef

(-num)=sgbook:N, (-pred)=book

(-per)=3

(-num)=sgC-structureandF-structureSNPmanNVPDettheVNPbookNDetareadssubj pred read(subj,obj)objspec defper 3num sgpred manspec defper 3num sgpred book如何計(jì)算?詞典+上下文無(wú)關(guān)規(guī)則+f描述S? NP (-subj)=ˉ

VP -=ˉVP? V -=ˉ

NP (-obj)=ˉNP?Det -=ˉ N -=ˉ-指父節(jié)點(diǎn)，ˉ指當(dāng)前節(jié)點(diǎn)例子 演示themanreadsabook *themanreadabookCoherence&CompletenessPA-StructureCoherence:任何有意義的語(yǔ)義結(jié)構(gòu)都必須在PA-Structure中出現(xiàn)Completeness:PA-Structure中出現(xiàn)的值都必須有與其對(duì)應(yīng)的語(yǔ)義結(jié)構(gòu)PPAttachmentsubj pred give(subj,obj,toobj)objtospec defper 3num sgpred manspec defper 3num sgpred bookprep toobjspec defper 3num sgpred womansubj pred see(subj,obj)objwith

spec defper 3num sgpred womanspec defper 3num sgpred manprep withobjspec defper 3num sgpred teles.Themangivesthebooktothewoman.thewomanseesthemanwiththetelescopeFUGFunctionalUnificationGrammar功能合一語(yǔ)法MartinKay,1979,FunctionalGrammar,InProceedingsofthe4thAnnualMeetingoftheBerkeleyLinguisticsSociety.MartinKay,1985,ParsinginFunctionalGrammar,InD.Dowty,L.Karttunen,andA.Zwickyeds,NaturalLanguageParsing,CambridgeUniversityPress,Cambridge,1985.GPSGGeneralizedPhraseStructureGra