  We describe a compiler which translates a set of HPSG lexical rules and their
interaction into definite relations used to constrain lexical entries. The
compiler ensures automatic transfer of properties unchanged by a lexical rule.
Thus an operational semantics for the full lexical rule mechanism as used in
HPSG linguistics is provided. Program transformation techniques are used to
advance the resulting encoding. The final output constitutes a computational
counterpart of the linguistic generalizations captured by lexical rules and
allows ``on the fly'' application.
