Syntactic Theory - Introduction
Transcript of Syntactic Theory - Introduction
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Syntactic TheoryIntroduction
Yi Zhang & Antske Fokkens
Department of Computational LinguisticsSaarland University
October 15, 2009
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Syntax: What does it mean?
We can view syntax/syntactic theory in a number of ways, twoof which are the following:
I Psychological way/model: syntactic structures correspondto what is in the heads of speakers and hearers
I Computational way/model: syntactic structures are formalobjects which can be mathematically treated/manipulated
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Syntactic Analysis
I Focus on collection of words and rules with which wegenerate
I strings of those words (weak generative power)I structures which license strings of those words (strong
generative power)I Syntax attempts to capture the nature of those rules:
1. Colorless green ideas sleep furiously2. *Furiously sleep ideas green colorless.3. *Sally talk to man.4. Sally talks to a man.
I What generalizations are needed to capture the differencebetween grammatical and ungrammatical sentences?
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Why is the Study of Syntax Relevant?
[Sag, Watson and Bender, 2003]
I A window on the structure of the mindI Innateness of the language faculty (Chomsky)
I Universal GrammarI A window on the mind’s activity
I Cognitive processI Ambiguity management
I Natural language technologiesI ParsingI GenerationI Grammar checking
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Why is the Study of Syntax Relevant?
[Sag, Watson and Bender, 2003]
I A window on the structure of the mindI Innateness of the language faculty (Chomsky)
I Universal GrammarI A window on the mind’s activity
I Cognitive processI Ambiguity management
I Natural language technologiesI ParsingI GenerationI Grammar checking
![Page 6: Syntactic Theory - Introduction](https://reader030.fdocuments.net/reader030/viewer/2022012723/61b4fe0e21f3921da8747d2b/html5/thumbnails/6.jpg)
Why is the Study of Syntax Relevant?
[Sag, Watson and Bender, 2003]
I A window on the structure of the mindI Innateness of the language faculty (Chomsky)
I Universal GrammarI A window on the mind’s activity
I Cognitive processI Ambiguity management
I Natural language technologiesI ParsingI GenerationI Grammar checking
![Page 7: Syntactic Theory - Introduction](https://reader030.fdocuments.net/reader030/viewer/2022012723/61b4fe0e21f3921da8747d2b/html5/thumbnails/7.jpg)
Why is the Study of Syntax Relevant?
[Sag, Watson and Bender, 2003]
I A window on the structure of the mindI Innateness of the language faculty (Chomsky)
I Universal GrammarI A window on the mind’s activity
I Cognitive processI Ambiguity management
I Natural language technologiesI ParsingI GenerationI Grammar checking
![Page 8: Syntactic Theory - Introduction](https://reader030.fdocuments.net/reader030/viewer/2022012723/61b4fe0e21f3921da8747d2b/html5/thumbnails/8.jpg)
Why is the Study of Syntax Relevant?
[Sag, Watson and Bender, 2003]
I A window on the structure of the mindI Innateness of the language faculty (Chomsky)
I Universal GrammarI A window on the mind’s activity
I Cognitive processI Ambiguity management
I Natural language technologiesI ParsingI GenerationI Grammar checking
![Page 9: Syntactic Theory - Introduction](https://reader030.fdocuments.net/reader030/viewer/2022012723/61b4fe0e21f3921da8747d2b/html5/thumbnails/9.jpg)
Why is the Study of Syntax Relevant?
[Sag, Watson and Bender, 2003]
I A window on the structure of the mindI Innateness of the language faculty (Chomsky)
I Universal GrammarI A window on the mind’s activity
I Cognitive processI Ambiguity management
I Natural language technologiesI ParsingI GenerationI Grammar checking
![Page 10: Syntactic Theory - Introduction](https://reader030.fdocuments.net/reader030/viewer/2022012723/61b4fe0e21f3921da8747d2b/html5/thumbnails/10.jpg)
Two Conceptions of Grammar
Prescriptive grammar
Consists of admonitions not to use certain forms orconstructions that are common in everyday speech:
I Never split an infinitive.I A preposition is a bad word to end a sentence with.
Human language is a phenomenon amenable to scientificinvestigation, rather than something to be regulated by thedecrees of authorities
Natural phenomena can NOT be legislated!
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Two Conceptions of Grammar
Prescriptive grammar
Consists of admonitions not to use certain forms orconstructions that are common in everyday speech:
I Never split an infinitive.I A preposition is a bad word to end a sentence with.
Human language is a phenomenon amenable to scientificinvestigation, rather than something to be regulated by thedecrees of authorities
Natural phenomena can NOT be legislated!
![Page 12: Syntactic Theory - Introduction](https://reader030.fdocuments.net/reader030/viewer/2022012723/61b4fe0e21f3921da8747d2b/html5/thumbnails/12.jpg)
Two Conceptions of Grammar
Prescriptive grammar
Consists of admonitions not to use certain forms orconstructions that are common in everyday speech:
I Never split an infinitive.I A preposition is a bad word to end a sentence with.
Human language is a phenomenon amenable to scientificinvestigation, rather than something to be regulated by thedecrees of authorities
Natural phenomena can NOT be legislated!
![Page 13: Syntactic Theory - Introduction](https://reader030.fdocuments.net/reader030/viewer/2022012723/61b4fe0e21f3921da8747d2b/html5/thumbnails/13.jpg)
Two Conceptions of Grammar
Prescriptive grammar
Consists of admonitions not to use certain forms orconstructions that are common in everyday speech:
I Never split an infinitive.I A preposition is a bad word to end a sentence with.
Human language is a phenomenon amenable to scientificinvestigation, rather than something to be regulated by thedecrees of authorities
Natural phenomena can NOT be legislated!
![Page 14: Syntactic Theory - Introduction](https://reader030.fdocuments.net/reader030/viewer/2022012723/61b4fe0e21f3921da8747d2b/html5/thumbnails/14.jpg)
Two Conceptions of Grammar
Prescriptive grammar
Consists of admonitions not to use certain forms orconstructions that are common in everyday speech:
I Never split an infinitive.I A preposition is a bad word to end a sentence with.
Human language is a phenomenon amenable to scientificinvestigation, rather than something to be regulated by thedecrees of authorities
Natural phenomena can NOT be legislated!
![Page 15: Syntactic Theory - Introduction](https://reader030.fdocuments.net/reader030/viewer/2022012723/61b4fe0e21f3921da8747d2b/html5/thumbnails/15.jpg)
Two Conceptions of Grammar
Descriptive grammar
I Observes language and creates conceptual categories forit without establishing rules of language
I Consults intuitions of native speakers on what soundsgood
1. They saw Pat with Chris.2. They saw Pat and Chris.3. Who did they see Pat with?4. * Who did they see Pat and?
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Syntax vs. Grammar
Two terms are in many cases used interchangeably, but
Syntax contrasts with semantics, morphology and phonology,and focus on the way words are put together into phrases, andphrases into sentences, although the boundaries are notalways sharp.
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Grammar Formalisms
Computational grammar formalisms share several propertiesI Descriptive adequacyI Precise encodingI Constrained formalism
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Descriptive Adequacy
Some researchers try to explain the underlying mechanisms,but we are most concerned with being able to describelinguistic phenomena
I Provide a structural description for every well-formedsentence
I Give us an accurate encoding of a languageI Give us broad-coverage, i.e., can (try to) describe all of a
language
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Precise Encoding
Mathematical Formalism: formal way to generate sets ofstrings or structures
Precisely define:I elementary structuresI ways of combining those structures
Such an emphasis on mathematical precision makes thesegrammar formalism more easily implementable
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Constrained Formalism
A formalism must be constrained:
I Linguistic motivation: limits the scope of the theory ofgrammar
I Computational motivation: allows us to define efficientprocessing models
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Simplistic Syntactic Theory Example IList as grammars
A grammar consists of a list of all the well-formedsentences in the language
I Some sentences go on and on.
I Some sentences go on and on and on.
I Some sentences go on and on and on and on.
I . . .
I Grammar G1 is defined by the language L it self, as a set ofstrings G1 = {si |si ∈ L }
I Weak expressive power: cannot enumerate all possiblesentences in a language
I No (useful) structure
I No generalization over linguistic phenomena
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Simplistic Syntactic Theory Example IList as grammars
A grammar consists of a list of all the well-formedsentences in the language
I Some sentences go on and on.
I Some sentences go on and on and on.
I Some sentences go on and on and on and on.
I . . .
I Grammar G1 is defined by the language L it self, as a set ofstrings G1 = {si |si ∈ L }
I Weak expressive power: cannot enumerate all possiblesentences in a language
I No (useful) structure
I No generalization over linguistic phenomena
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Simplistic Syntactic Theory Example IList as grammars
A grammar consists of a list of all the well-formedsentences in the language
I Some sentences go on and on.
I Some sentences go on and on and on.
I Some sentences go on and on and on and on.
I . . .
I Grammar G1 is defined by the language L it self, as a set ofstrings G1 = {si |si ∈ L }
I Weak expressive power: cannot enumerate all possiblesentences in a language
I No (useful) structure
I No generalization over linguistic phenomena
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Simplistic Syntactic Theory Example IIRegular Expressions
Regular Expressions, i.e. patterns making use ofKleene star (and Kleene plus), parentheses foroptionality, and the vertical bar for alternatives, can beused to describe grammars
I G2: Some sentences go on [and on]+.
I Insufficient description power to capture generalizations
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Syntactic Theories to be Reviewed
In this course, we will introduce the following linguisticframeworks
I Chomskyan Transformational Tradition & MinimalismI Dependency GrammarI Tree Adjoining GrammarI Lexical Functional GrammarI Head-Driven Phrase Structure Grammar
With particular focus on the LFG and HPSG
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Organizational Matters
I Time: Tuesday 16:15 - 17:45, Thursday 14:15 - 15:45I Location: Seminar Room, C72I Office hours: Thursday 13:00 - 14:00 (after email contact)I Credit Points: 6 CPI Course Homepage:
http://www.coli.uni-saarland.de/courses/syntactic-theory-09/
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Lectures, Exercises, and Exam
I Regular attendance of the lectures are requiredI Exercises needs to be submitted in, and will be correctedI One must “pass” at least half of the exercises to be
qualified for the final exam