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Techniques of Grammatical Analysis Rajat Kumar Mohanty [email protected] IIT Bombay What is Grammar? • A theory of language • A theory of competence of a native speaker • An explicit model of competence • A finite set of rules What are the requirements? • A model of competence – Should be able to generate an infinite set of grammatical sentences of the language – Should not generate any ungrammatical ones – Should be able to account for ambiguities – If two sentences are understood to have same meaning, the grammar should give the same structure for both at some level – If two sentences are understood to have different internal relationship, the grammar should assign different structural description Techniques of Grammatical Analysis • Two main devices – Breaking up a string • Sequential • Hierarchical • Transformational – Labeling the constituents • Morphological • Categorial • Functional • A grammar may combine any of these devices for grammatical analysis. Grammatical Analysis Techniques Breaking up Sequential Transformational Hierarchical Labeling Morphological Functional Categorial Breaking up and Labeling – Sequential Breaking up • Sequential Breaking up and Morphological labeling • Sequential Breaking up and Categorial labeling • Sequential Breaking up and Functional labeling – Hierarchical Breaking up • Hierarchical Breaking up and Categorial Labeling • Hierarchical Breaking up and Functional Labeling Sequential Breaking up • This device breaks up a sentence into a sequence of morphemes the + boy + s + kill + ed + the + un + happy + rat + s raam + ne + dande + se + saap + ko + maar + aa • If a sentence is understood in two different ways, a grammar should give two corresponding descriptions – They + can + fish • They are able to fish • They put fish in cans Sequential Breaking up and Morphological labeling After breaking up a sentence, we can give morphological labels to each units the + boy + s + kill + ed + the + un + happy + rat + s word stem affix stem affix word affix stem stem affix raam + ne + dande + se + saap + ko + maar + aa word affix word affix word affix word affix Sequential Breaking up and Categorical Labeling • This boy can solve the problem S This boy Det N can Aux solve V the Det problem N Sequential Breaking up and Categorical Labeling (…continued) • They Pronoun • They Pronoun can fish Aux Verb can fish Verb Noun Sequential Breaking up and Categorical Labeling (…continued) • They called Pronoun Verb her a taxi Pronoun Article Noun – They said she was a taxi – They called a taxi for her Sequential Breaking up and Functional labeling They called her a taxi Subject Verbal IO DO called her a taxi They Subject Verbal DO Object Complement Sequential Breaking up and Functional labeling (…continued) Old men modifier Head and women coordinator Head Hierarchical Breaking up • This device breaks up a sentence into its constituents at different hierarchies or levels Old men and women Old men and women men and women Old men and women Old men Old men and women Hierarchical Breaking up and Categorial Labeling Poor ADJ NP John ran away N V ADV VP Hierarchical Breaking up and Functional Labeling • Immediate Constituent Analysis • Construction types in terms of the function of the constituents: – Predication (subject + predicate) – Modification (modifier + head) – Complementation (verbal + complement) – Subordination (subordinator + dependent unit) – Coordination (independent unit + coordinator + independent unit) In the morning, the sky looked much brighter Mod Mod Head Mod Head Verbal Sub DU Modifier Head Subject Complement Predicate Head Hierarchical Breaking up and Categorial /Functional Labeling • Hierarchical Breaking up coupled with Categorial /Functional Labeling is a very powerful device • But there are ambiguities which demand something more powerful Love of God • Someone loves God • God loves someone Love of God Noun Phrase love Love of God Prepositional Phrase of God Head love Modifier Sub- DU of God Generative Grammar • A generative grammar – generates all the grammatical sentences of the language – rejects all the ungrammatical ones • It is free to choose and combine any of the techniques of breaking up and labeling • Depending upon what tools the grammar combines, we have different types of grammar Types of Generative Grammar • Finite State Model (sequential) • Phrase Structure Model (sequential + hierarchical) • Transformational Model (sequential + hierarchical + transformational) Phrase Structure Model • Inadequacies – Ambiguity – Paraphrase Relationship – Constructional Homonymy Ambiguity • If a sentence is understood to have two meanings, a grammar should give two corresponding structural descriptions • PS grammar fails to meet this demand • The shooting of the hunters – The hunter shot someone – Someone shot the hunters NP PP NP Det the N shooting P of NP Det N the hunters Paraphrase Relationship • If two sentences are understood to have the same meaning, a grammar should give the same structural description for the two sentences at some level • PS grammar fails to meet this demand • Examples – The boy slapped the girl – The girl was slapped by the boy S VP NP Det The N boy V slapped NP Det N the girl S VP NP Det The N girl V PP Aux V P was slapped by NP the boy Constructional Homonymy • If two sentences are not understood the same way, a grammar should give two structural descriptions • PS grammar cannot do this – The audience was asked to leave by the side-door – The audience was asked to leave by the chairman S VP NP Det V N Aux Inf. Phr V VP Inf. V PP P NP Det The audience was asked to leave by the N Sidedoor S VP NP Det V N Aux Inf. Phr V VP Inf. V PP P NP Det The audience was asked to leave by the N Chairman Transformational Model • If a generative grammar makes use of all the three -sequential -hierarchical and -transformational is called a Transformational grammar. PS model • Makes use of PS rules exclusively • PS rules generate surface structure Transformational model • Makes use of PS rules and transformational rules • PS rules generate DS • DS is converted into the surface structure by transformational rules PS grammar Surface Structure PS rules Transformational grammar PS rules Deep Structure Transformation Surface Structure Why wasn’t he punished? • PS rules: S NP – VP VP V - NP – PP V Aux – V Aux (Tense)-(Modal)-(Perf)-(Prog) Tense {pres/past} NP (PreDet) - (Det) - (Ord) -(Quan) -(AP)-N Lexical substitution S VP NP VG Aux NP PP V Tense Someone past punish him for some reason Why wasn’t he punished? (…continued) • Transformations – Passivization – Agent deletion – Negation – Neg. Contraction – Wh- substitution – Interrogation – Wh- fronting – Affix switch Passivization S VP NP VG Aux Tense He past PP V Pass be en punish P PP NP N by someone for Some reason Agent Deletion S VP NP VG Aux Tense He past PP V Pass be en punish for some reason Negation S VP NP VG Aux Tense He past PP V Pass be not en punish for some reason Neg. Contraction S VP NP VG Aux Tense He past PP V Pass be’not en punish for some reason WhSubstitution S VP NP VG Aux Tense He past WH V Pass be’not en punish why Interrogative S Aux VP NP VG WH V Tense past be’not he en punish why WH Aux S Wh-fronting NP VP VG V Tense why past be’not he en punish WH Aux S Affix switch NP VP VG Tense V be’not past punish why was’not he en punished Suggested Readings • Lyons, John. 1977. Chomsky. Fontana, London. • Palmer, Frank. Grammar • Crystal, David. Linguistics THANK YOU Q\A