Computational Morphology by Lexical Rules

In this paper we outline a lexical organization for Turkish that makes use of lexical rules for innections, 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. The resulting grammar architecture has morphology embedded in the lexicon. The design has been tested as part of an HPSG grammar for Turk-ish. Rebracketing in compounds and phrasal scope in aaxation present formidable diiculties for lexical rules. In terms of performance, run-time execution of the rules seems to be a far better alternative than precompilation. The latter causes exponential growth in the lexicon due to intensive use of innections and derivations in Turkish.