tailieunhanh - Báo cáo khoa học: "Coreference handling in XMG"

We claim that existing specification languages for tree based grammars fail to adequately support identifier managment. We then show that XMG (eXtensible MetaGrammar) provides a sophisticated treatment of identifiers which is effective in supporting a linguist-friendly grammar design. | Coreference handling in XMG Claire Gardent CNRS LORIA 615 rue du jardin botanique . 101 54602 Villers les Nancy CEDEX France Yannick Parmentier INRIA Lorraine 615 rue du jardin botanique . 101 54602 Villers les Nancy CEDEX France Abstract We claim that existing specification languages for tree based grammars fail to adequately support identifier managment. We then show that XMG extensible MetaGrammar provides a sophisticated treatment of identifiers which is effective in supporting a linguist-friendly grammar design. 1 Specifying tree-based grammars Whilst the development of standard unificationbased grammars is well supported by the design of formalisms such as PATR-II Ale or TDL Krieger and Schafer 1994 the situation is less well established for Tree-Based Grammars such as Tree Adjoining Grammars Joshi and Schabes 1997 Tree Description Grammars Kallmeyer 1996 or Interaction Grammars Perrier 2003 . Roughly two main types of specification formalism for Tree-Based Grammars can be distinguished formalisms based on tree fragments and non monotonic inheritance and formalisms based on tree descriptions and monotonic inheritance. The tree fragment approach is advocated in Evans et al. 1995 which proposes to encode lex-icalised tags using the DATR representation language1 . In this approach tree fragments are combined within a non monotonic inheritance hierarchy. Furthermore new fragments can be derived from existing ones by means of lexical rules. This first approach suffers from the procedural character of non-monotonic inheritance. In specifying the grammar the grammar writer must keep 1A tree based approach is also used in Becker 2000 but this time in combination with metarules. In that particular approach procedural aspects also come into play as the order in which metarules apply affect the results. in mind the order in which non-monotonic statements have been made so as to be able to predict how explicit .