Phrase structure rules in the context of "Transformational grammar"

Colorless green ideas sleep furiously was composed by Noam Chomsky in his 1957 book Syntactic Structures as an example of a sentence that is grammatically well-formed, but semantically nonsensical. The sentence was originally used in his 1955 thesis The Logical Structure of Linguistic Theory and in his 1956 paper "Three Models for the Description of Language". There is no obvious understandable meaning that can be derived from it, which demonstrates the distinction between syntax and semantics, and the idea that a syntactically well-formed sentence is not guaranteed to also be semantically well-formed. As an example of a category mistake, it was intended to show the inadequacy of certain probabilistic models of grammar, and the need for more structured models.

In linguistics, a grammatical construction is any syntactic string of words ranging from sentences over phrasal structures to certain complex lexemes, such as phrasal verbs.

Grammatical constructions form the primary unit of study in construction grammar theories. In construction grammar, cognitive grammar, and cognitive linguistics, a grammatical construction is a syntactic template that is paired with conventionalized semantic and pragmatic content. In generative frameworks, constructions are generally treated as epiphenomenal, being derived by the general syntactic rules of the language in question.

In linguistics, X-bar theory is a model of phrase structure and a theory of syntactic category formation that proposes a universal schema for how phrases are organized. It suggests that all phrases share a common underlying structure, regardless of their specific category (noun phrase, verb phrase, etc.). This structure, known as the X-bar schema, is based on the idea that every phrase (XP, X phrase) has a head, which determines the type (syntactic category) of the phrase (X).

The theory was first proposed by Noam Chomsky in 1970 reformulating the ideas of Zellig Harris (1951), and further developed by Ray Jackendoff (1974, 1977a, 1977b), along the lines of the theory of generative grammar put forth in the 1950s by Chomsky. It aimed to simplify and generalize the rules of grammar, addressing limitations of earlier phrase structure models. X-bar theory was an important step forward because it simplified the description of sentence structure. Earlier approaches needed many phrase structure rules, which went against the idea of a simple, underlying system for language. X-bar theory offered a more elegant and economical solution, aligned with the thesis of generative grammar.

Syntactic Structures is a seminal work in linguistics by American linguist Noam Chomsky, originally published in 1957. A short monograph of about a hundred pages, it is recognized as one of the most significant and influential linguistic studies of the 20th century. It contains the now-famous sentence "Colorless green ideas sleep furiously", which Chomsky offered as an example of a grammatically correct sentence that has no discernible meaning, thus arguing for the independence of syntax (the study of sentence structures) from semantics (the study of meaning).

Based on lecture notes he had prepared for his students at the Massachusetts Institute of Technology in the mid-1950s, Syntactic Structures was Chomsky's first book on linguistics and reflected the contemporary developments in early generative grammar. In it, Chomsky introduced his idea of a transformational generative grammar, succinctly synthesizing and integrating the concepts of transformation (pioneered by his mentor Zellig Harris, but used in a precise and integrative way by Chomsky), morphophonemic rules (introduced by Leonard Bloomfield) and an item-and-process style of grammar description (developed by Charles Hockett). Here, Chomsky's approach to syntax is fully formal (based on symbols and rules). At its base, Chomsky uses phrase structure rules, which break down sentences into smaller parts. These are combined with a new kind of rules which Chomsky called "transformations". This procedure gives rise to different sentence structures. Chomsky stated that this limited set of rules "generates" all and only the grammatical sentences of a given language, which are infinite in number (not too dissimilar to a notion introduced earlier by Danish linguist Louis Hjelmslev). Although not explicitly stated in the book itself, this way of study was later interpreted to have valued language's innate place in the mind over language as learned behavior,