The lexicon now plays a central role in our implementation of a Head-driven Phrase Structure G r a m m a r (HPSG), given the massive relocation into the lexicon of linguisticinformation that was carried by the phrase structure rules in the old G P S G system. HPSG's grammax contains fewer tha4z twenty (very general) rules; its predecessor required over 350 to achieve roughly the same coverage. This simplification of the grammax is made possible by an enrichment of the structure and content of lexical entries, using both inhcrit~nce mechanisms and lexical rules to represent thc linguistic.
