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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.
XTAG Project
http://www.cis.upenn.edu/~xtag