Lexical rules in constraint-based grammars
Ted Briscoe, Ann Copestake · 1999
Lexical rules have been used to cover a very diverse range of phenomena in constraintbased grammars. Examination of the full range of rules proposed shows that Carpenter's (1991) postulated upper bound on the length of list-valued attributes such as subcat in the lexicon cannot be maintained, leading to unrestricted generative capacity in constraint-based formalisms utilizing HPSG-style lexical rules. We argue that it is preferable to subdivide such rules into a class of semi-productive lexically-governed genuinely lexical rules, and a class of fully productive unary syntactic rules. We develop a restricted approach to lexical rules in a typed default feature structure (TDFS) framework (Lascarides et al., 1996; Lascarides and Copestake, forthcoming) which has enough expressivity to state, for example, rules of verb diathesis alternation, but which does not allow arbitrary manipulation of list-valued features. An interpretation of such lexical rules within a probabilistic version of a ...