Feature-Based, Lexicalized Tree Adjoining Grammars

The English grammar described in this report is based on the TAG formalism ([#!joshi75!#]), which has been extended to include lexicalization ([#!schabes88!#]), and unification-based feature structures ([#!vijay91!#]). Tree Adjoining Languages (TALs) fall into the class of mildly context-sensitive languages, and as such are more powerful than context free languages. The TAG formalism in general, and lexicalized TAGs in particular, are well-suited for linguistic applications. As first shown by [#!joshi85!#] and [#!kj87!#], the properties of TAGs permit us to encapsulate diverse syntactic phenomena in a very natural way. For example, TAG's extended domain of locality and its factoring of recursion from local dependencies lead, among other things, to a localization of so-called unbounded dependencies.