2 research outputs found
Description Theory, LTAGs and Underspecified Semantics
An attractive way to model
the relation between an underspecified syntactic representation and
its completions is to let the underspecified representation correspond
to a logical description and the completions to the
models of that description. This approach, which underlies the
Description Theory of (Marcus et al. 1983) has been integrated
in (Vijay-Shanker 1992) with a pure unification approach to
Lexicalized Tree-Adjoining
Grammars (Joshi et al.\ 1975, Schabes 1990). We generalize
Description Theory by integrating semantic
information, that is, we propose to tackle both syntactic and
semantic underspecification using descriptions
XMG : eXtensible MetaGrammar
International audienceIn this article, we introduce eXtensible MetaGrammar (xmg), a framework for specifying tree-based grammars such as Feature-Based Lexicalised Tree-Adjoining Grammars (FB-LTAG) and Interaction Grammars (IG). We argue that xmg displays three features which facilitate both grammar writing and a fast prototyping of tree-based grammars. Firstly, \xmg\ is fully declarative. For instance, it permits a declarative treatment of diathesis that markedly departs from the procedural lexical rules often used to specify tree-based grammars. Secondly, the \xmg\ language has a high notational expressivity in that it supports multiple linguistic dimensions, inheritance and a sophisticated treatment of identifiers. Thirdly, xmg is extensible in that its computational architecture facilitates the extension to other linguistic formalisms. We explain how this architecture naturally supports the design of three linguistic formalisms namely, FB-LTAG, IG, and Multi-Component Tree-Adjoining Grammar (MC-TAG). We further show how it permits a straightforward integration of additional mechanisms such as linguistic and formal principles. To further illustrate the declarativity, notational expressivity and extensibility of \xmg , we describe the methodology used to specify an FB-LTAG for French augmented with a unification-based compositional semantics. This illustrates both how xmg facilitates the modelling of the tree fragment hierarchies required to specify tree-based grammars and of a syntax/semantics interface between semantic representations and syntactic trees. Finally, we briefly report on several grammars for French, English and German that were implemented using \xmg\ and compare \xmg\ to other existing grammar specification frameworks for tree-based grammars