A Computational Treatment of Lexical Rules in HPSG as Covariation in Lexical Entries

This paper proposes a new computational treatment of lexical rules as used in the HPSG framework. A compiler is described which translates a set of lexical rules and their interaction into a definite clause encoding, which is called by the base lexical entries in the lexicon. This way, the disjunctive possibilities arising from lexical rule application are encoded as systematic covariation in the specification of lexical entries. The compiler ensures the automatic transfer of properties not changed by a lexical rule. Program transformation techniques are used to advance the encoding. The final output of the compiler constitutes an efficient computational counterpart of the linguistic generalizations captured by lexical rules and allows on-the-fly application of lexical rules.