  In this paper we outline a lexical organization for Turkish that makes use of
lexical rules for inflections, derivations, and lexical category changes to
control the proliferation of lexical entries. Lexical rules handle changes in
grammatical roles, enforce type constraints, and control the mapping of
subcategorization frames in valency-changing operations. A lexical inheritance
hierarchy facilitates the enforcement of type constraints. Semantic
compositions in inflections and derivations are constrained by the properties
of the terms and predicates.
  The design has been tested as part of a HPSG grammar for Turkish. In terms of
performance, run-time execution of the rules seems to be a far better
alternative than pre-compilation. The latter causes exponential growth in the
lexicon due to intensive use of inflections and derivations in Turkish.
