phrase-structure grammar

views updated

phrase-structure grammar (PSG) A grammar that contains rules which are capable of both generating strings of linguistic elements and providing a constituent analysis of the strings. In their original form, phrase-structure grammars took the form of a set of rewrite rules, for example S → NP + VP

(which reads rewrite S as NP (noun phrase) + VP (verb phrase)). Various distinctions have been made between different classes of phrase-structure grammar, primarily between context-sensitive and context-free grammars.