Broad-coverage grammars tend to be very ambiguous. When such a grammar has to be used on a restricted domain, it can be desirable to specialize it, i.e. to trade part of the coverage for a reduction in ambiguity. This paper presents a novel formulation of grammar specialization as an optimization problem, in which the search is guided by a global measure combining coverage and ambiguity. The method, applicable to any unification grammar with a phrase-structure backbone, is shown to be effective in specializing a broad-coverage LFG for French.
