GF Tutorial

Description

G F T utorial
M uhammad H umayoun
mhuma [at] univ-sav oie. fr
PhD student, Department of Mathematic s (LAMA)
Universite de s avoie
Ba sed on the course named "N atural Lan guage T echnology", talks and tutorials given by
Aarne R anta (aarn e [at] cs.chalmers. se) 1N atural Language T echnology and state
of the art T echnologies
 6000-8000 living langua ges in th e worl d
 Trans lation Sy stems: either limited or of low quality
 Dialogue Sys tems: bo th li mited an d of low quali ty
 Teac hing: no t use d as mu ch as it cou ld be
 Web search: advanced for s ome languages but unknown
 Error m essages: ba d qua lity throu gh " canned tex t": you ha ve 1
message(s)
 Soft ware localization: lists o f can ned text sent ences
2N atural vs programming languages
 G enerally, G rammar = S yntax + S emantics
 For a programming language, the grammar is part
of its specification and implementation
 N atural language is not defined by a grammar.
grammar of a N L is a research problem
 A part of a language technology application is often
to solve a part of this research problem!
3T he O bjective of these T utorials
 Building some applications in three sub disciplines
of N LT using G F
 M orphology: theory of w ords a nd th eir fo rms
 Sy ntax: theory of text and sentence st ructure
 Sem antics: theory of meaning
 Understanding what is needed for high-quality
translation, dialogues etc and their specific
solutions in G F
4W hat will we cover
 T utorial 1: ...

Sujets

• Mécanisme (philosophie)
• Opera IX
• Syntaxe spatiale
• Dictionnaire historique de la Suisse
• Rat-taupe nu
• Kiss-in

Informations

• Publié par: Ummo
• Nombre de lectures: 81
• Langue: English

Extrait

GF Tutorial

Muhammad Humayoun

mhuma [at] univ-savoie.fr

PhD student, Department of Mathematics (LAMA)

Universite de savoie

Based on the course named "Natural Language Technology", talks and tutorials given by Aarne Ranta (aarne [at] cs.chalmers.se) 1

aNcenhlogo yna dtstural Language T golonhcesei tof e at  Trt ahe italthy ugro"ch ennaet d:"txuoy Error emssgase :ab duq e 1h va

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message(s)

6000-8000living languages in the world

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Web search some languages but unknown: advanced for

Software localization: lists of canned text sentences

Translation Systems quality: either limited or of low

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Dialogue Systems quality low: both limited and of

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Teaching: not used as much as it could be

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Natural vs programming languages

Generally,Grammar = Syntax + Semantics

For a programming language, the grammar is part

of its specification and implementation

Natural language is not defined by a grammar.

grammar of a NL is aresearch problem

A part of a language technology application is often

to solve a part of this research problem!

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The Objective of these Tutorials

Building some applications in three sub disciplines of NLT using GF

   Morphology: theory of words and their forms

   Syntax: theory of text and sentence structure

   Semantics: theory of meaning Understanding what is needed for high-quality translation, dialogues etc and their specific solutions in GF

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What will we cover

Tutorial 1: Morphology & Lexicon

Tutorial 2: Syntax and Translation systems

Tutorial 3: Syntax, Translation and Formal Proofs

Tutorial 4: Syntax and Semantics

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What is GF?

 Grammar formalism based on type theory  Special-purpose functional programming language having a powerful type system  Fundamental structure:

       grammar = abstract syntax + concrete syntaxes  Abstract syntax= semantic conditions (correct    syntactic structures/trees of a language)  Concrete syntax= mapping abstract syn

Concrete syntax= mapping abstract syntax into strings along-with the grammatical features for a language (and back, by reversibility)

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Morphology

Part of speech or word class (Nouns, Verbs, Adjectives, Adverbs etc) GF follows word-and-paradigm model of morphology in which word forms are created by combining different morphs Inflection tables =Display all forms of a word.

Example: English regular nouns

Singular Nominative rat Genitive rat's

Plural rats rats '

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Stems, endings, morphs, morphemes

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A word form can often be analysed to parts:   (prefix), dress (stem), -ed (suffix) un-Undressed ---  Carelessness --- care (stem), -less (suffix), -ness (suffix) All these significant parts are calledmorphs. Amorphemeis an abstraction over different morphs that have the same function. For instance, s and es are variants of the plural morpheme: boy + s, kiss + es Morphological analysis = analysis into morphemes (in the abstract sense of parameter description) boys --> boy +Nom +Pl babies --> baby +Gen +Pl ' Thusanalysis = lemma + tags

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Parameters

The different form descriptions are grouped into types.  Examples of such types and their values: number: singular, plural (Arabic also: dual) gender: masculine, feminine (French, Arabic, Urdu/Hindi) / masculine, feminine, neuter (German, Latin, English) case: nominative, genitive (Swedish) / nominative, accusative, dative, genitive (German) Heavily dependent on language!  A word class is of morphologically defined by telling what type parameters its forms depend on. Parametric vs. inherent features  To define  inherenta word class, we should also tell what features attach to it. Cf. class in Java:  method: inflection for different combinations of parameters  attributes: inherent features

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Defining morphology of a language

Type system: define parameter types and word classes

Inflection engine: define all paradigms for all word classes

Lexicon: list all words with their word classes and paradigms.

The definitions can be made with stg like 100 + 1000 + 10000 lines of code, for a "medium hard" language likeFrench.

Englishneeds less types and paradigms, but more lexicon.

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Uses of a morphology

 Synthesis inflection generate table. word,: given a dictionary  Analysis word class, and: given a word form, return lemma, form description (which can be ambiguous)

Implementing morphology  General-purpose programming languages: Haskell, Caml, Java, C,... need to define the types and data structures of the type system, the inflection engine, and the lexicon. And also an analysis program! ex.Functional Morphology(a Haskell library for morphology development). Special-purpose morphology languages. The most well- known:XFST, based on regular expressions. GF, Further it extends to syntax seamlessly from morphology and semantics. 11

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