Translating a Unification Grammar with Disjunctions into Logical Constraints

This paper proposes a method for generating a logicalconstraint-based internal representation from a unification grammar formalism with disjunctive information. Unification grammar formalisms based on path equations and lists of pairs of labels and values are better than those based on first-order terms in that the former is easier to describe and to understand. Parsing with term-based internal representations is more efficient than parsing with graph-based representations. Therefore, it is effective to translate unification grammar formalism based on path equations and lists of pairs of labels and values into a term-based internal representation. Previous translation methods cannot deal with disjunctive feature descriptions, which reduce redundancies in the grammar and make parsing efficient. Since the proposed method translates a formalism without expanding disjunctions, parsing with the resulting representation is efficient.