Generalized phrase structure grammar

Generalized phrase structure grammar (GPSG) is a framework for describing the syntax and semantics of natural languages.

Their book Generalized Phrase Structure Grammar, published in 1985, is the main monograph on GPSG, especially as it applies to English syntax.

In fact, the notational extensions to context-free grammars (CFGs) developed in GPSG are claimed to make transformations redundant.

Among these conventions are a sophisticated feature structure system and so-called "meta-rules", which are rules generating the productions of a context-free grammar.

[3] However, it has been argued (for example by Robert Berwick) that these extensions require parsing algorithms of a higher order of computational complexity than those used for basic CFGs.