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Phrase Structure Grammars for Natural Languages
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Intro
Using natural languages is a crucial human ability that has so
far proved difficult to transfer to computers.
Crucial to our progress in this domain is a better understanding
of the empirical properties of natural languages and the development
of linguistic formalisms appropriate both for analyzing these
properties and for computer application, such as the newly developed
Head-driven Phrase Structure Grammar framework.
Natural Language Processing (NLP) is one of the central domains of investigation in
artificial intelligence. Developments in this domain crucially depend on progress in our
theoretical and empirical understanding of the way natural languages work. Head-driven
Phrase Structure Grammar (HPSG, cf. Pollard and Sag 1987, 1994) provides a
framework which is especially suitable both for purely linguistic research and for NLP
applications of the results obtained. On the one hand, it rests on a careful and coherent
formalism (the logic of typed feature structures) which is well-suited for computational
applications, providing reversibility, declarativeness and the use of partial descriptions.
On the other hand, it integrates many essential empirical and theoretical advances of the
major frameworks that have preceded it. Apart from English, which is the most
completely described, the HPSG framework has been adopted in studies of various other
languages, e.g. German, Korean, Italian, Japanese. Among other projects, it is the
framework adopted for Verbmobil a German/English/Japanese interpretation project
funded by the German government.
A Phrase Structure Grammar of French
Numerous syntactic phenomena in French have been studied in depth by traditional
grammarians as well as by modern generative linguists. However, neither research
tradition has the resources necessary to provide a coherent and explicit model for
studying the entire body of French syntactic phenomena. In collaboration with Anne
AbeillÈ and DaniËle Godard (UniversitÈ Paris 7) and Ivan Sag (Stanford University), we
have decided to systematically take up the principle syntactic phenomena of the French
language once again, in order to obtain a detailed and reasonably formalized description
which constitutes what can be termed a phrase structure grammar of French. Major
results have already been obtained in the treatment of auxiliaries, causative and
perception verbs, clitic complements, and extraction out of noun phrases. Our current
research topics include: (i) verbal constructions: passives, reflexives (inherent, middle
and true reflexives), impersonal constructions, inverted constructions, support verbs; (ii)
noun phrases: argument structure, determiners, prepositions; (iii) verb complementation:
infinitives and complements with que, raising vs. control verbs; (iii) negation; (iv)
coordination.
English Verbal Complementation
The analysis of the types of complement structures that different verbs allow is a central
topic in linguistics, involving syntactic, semantic and even morphophonological
properties of verbs. For instance, though both They sent a message to Kim and They
sent a message to Chicago are acceptable sentences, the acceptable variant They sent
Kim a message contrasts with the unacceptable *They sent Chicago a message.
Similarly the verb begin allows both infinitival and gerund complements (Kim began to
eat; Kim began eating) whereas finish allows only gerunds (Kim finished eating; *Kim
finished to eat). It is theoretically and practically crucial to understand to what extent
such alternations are arbitrary, or can be motivated in terms of meaning or other
properties of the verb. HPSG provides an ideally suited framework for discussing such
alternations, since the feature structures describing verbs provide simultaneous access to
syntactic, semantic and morphophonological information, thereby making it easy to state
principled explanations of relevant correlations. The present project aims to explain
complementation alternations in small groups of semantically similar verbs, on the basis
of large corpora of examples of actual uses of the verbs obtained from large English text
data banks.
Strong Generative Capacity
Crucial to a well-conceived implementation of linguistic formalisms is an understanding
of the implicit semantics that underlies them. Building on Chomsky's original definition
of Strong Generative Capacity (SGC) as the set of derivations produced by a grammar,
we propose a framework where SGC is understood as providing model-theroretic
semantic interpretations for the formalisms employed by linguistic theories and are
currently applying it to a broad range of such theories.
[ Philip H. Miller ]
Selected references
- P. H. Miller.
- Clitics and Constituents in Phrase Structure Grammar.
New York: Garland, 1992.
- P. H. Miller.
- Strong Generative Capacity
The Semantics of Linguistic Formalism. Stanford: CSLI Press, to appear.
- P. H. Miller et I. A. Sag.
- Une analyse lexicaliste des affixes pronominaux du franÁais.
Revue quÈbÈcoise de linguistique, 1995.
- A. AbeillÈ, D. Godard, and P.H. Miller.
- The syntactic structure of French causative constructions.
Unpublished ms. UniversitÈ Paris 7 et UniversitÈ Libre de Bruxelles.
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