Adjective ordering

At this point, the treatment of adjectives in the XTAG English grammar does not include selectional or ordering restrictions.^24.1 Consequently, any adjective can adjoin onto any noun and on top of any other adjective already modifying a noun. All of the modified noun phrases shown in ((499))-((502)) currently parse.

(498)0(498

(499)

big green bugs  (499)0(499

(500)

big green ideas  (500)0(500

(501)

colorless green ideas  (501)0(501

(502)

$\ast$green big ideas 

While ((500))-((502)) are all semantically anomalous, ((502)) also suffers from an ordering problem that makes it seem ungrammatical as well. Since the XTAG grammar focuses on syntactic constructions, it should accept ((499))-((501)) but not ((502)). Both the auxiliary and determiner ordering systems are structured on the idea that certain types of lexical items (specified by features) can adjoin onto some types of lexical items, but not others. We believe that an analysis of adjectival ordering would follow the same type of mechanism.