Generative grammar is a linguistic theory that regards grammar as a system of rules that generates exactly those combinations of words that form grammatical sentences in a given language. Noam Chomsky first used the term in relation to the theoretical linguistics of grammar that he developed in the late 1950s. Linguists who follow the generative approach have been called generativists. The generative school has focused on the study of syntax and addressed other aspects of a language's structure, including morphology and phonology.There are a number of different approaches to generative grammar. Common to all is the effort to come up with a set of rules or principles that formally defines each and every one of the members of the set of well-formed expressions of a natural language. The term generative grammar has been associated with at least the following schools of linguistics:Generative grammars can be described and compared with the aid of the Chomsky hierarchy (proposed by Chomsky in the 1950s). This sets out a series of types of formal grammars with increasing expressive power. Among the simplest types are the regular grammars (type 3); Chomsky claims that these are not adequate as models for human language, because of the allowance of the center-embedding of strings within strings, in all natural human languages.Generative grammar has been used to a limited extent in music theory and analysis since the 1980s. The most well-known approaches were developed by Mark Steedman as well as Fred Lerdahl and Ray Jackendoff, who formalized and extended ideas from Schenkerian analysis. More recently, such early generative approaches to music were further developed and extended by various scholars. The theory of generative grammar has been manipulated by the Sun Ra Revival Post-Krautrock Archestra in the development of their post-structuralist lyrics. This is particularly emphasised in their song 'Sun Ra Meets Terry Lee'. French Composer Philippe Manoury applied the systematic of generative grammar to the field of contemporary classical music.