chomsky

The formalism of context-free grammars was developed in the mid-1950s by Noam Chomsky, and also their classification as a special type of formal grammar (which he called phrase-structure grammars).



A context-free grammar provides a simple and mathematically precise mechanism for describing the methods by which phrases in some natural language are built from smaller blocks, capturing the "block structure" of sentences in a natural way. Its simplicity makes the formalism amenable to rigorous mathematical study. Important features of natural language syntax such as agreement and reference are not part of the context-free grammar, but the basic recursive structure of sentences, the way in which clauses nest inside other clauses, and the way in which lists of adjectives and adverbs are swallowed by nouns and verbs, is described exactly.



In Chomsky's generative grammar framework, the syntax of natural language was described by a context-free rules combined with transformation rules. In later work (e.g. Chomsky 1981), the idea of formulating a grammar consisting of explicit rewrite rules was abandoned. In other generative frameworks, e.g. Generalized Phrase Structure Grammar (Gazdar et al. 1985), context-free grammars were taken to be the mechanism for the entire syntax, eliminating transformations.

—A formal grammar (sometimes simply called a grammar) is a set of formation rules for strings in a formal language. The rules describe how to form strings from the language's alphabet that are valid according to the language's syntax. A grammar does not describe the meaning of the strings or what can be done with them in whatever context—only their form.


—Formal language theory, the discipline which studies formal grammars and languages, is a branch of applied mathematics. Its applications are found in theoretical computer science, theoretical linguistics, formal semantics, mathematical logic, and other areas.


—A formal grammar is a set of rules for rewriting strings, along with a "start symbol" from which rewriting must start. Therefore, a grammar is usually thought of as a language generator. However, it can also sometimes be used as the basis for a "recognizer"—a function in computing that determines whether a given string belongs to the language or is grammatically incorrect. To describe such recognizers, formal language theory uses separate formalisms, known as automata theory. One of the interesting results of automata theory is that it is not possible to design a recognizer for certain formal languages.
—Parsing is the process of recognizing an utterance (a string in natural languages) by breaking it down to a set of symbols and analyzing each one against the grammar of the language. Most languages have the meanings of their utterances structured according to their syntax—a practice known as compositional semantics . As a result, the first step to describing the meaning of an utterance in language is to break it down part by part and look at its analyzed form (known as its parse tree in computer science, and as its deep structure in generative grammar).
—The linguistic formalism derived from Chomsky can be characterized by a focus on innate
universal grammar (UG), and a disregard for the role of stimuli. According to this position,
language use is only relevant in triggering the innate structures. With regard to the tradition,
Chomsky’s position can be characterized as a continuation of essential principles of
structuralist theory from Sauss...ure (Givón 2001). This is particularly the case for Saussure’s
principles of abstractness and arbitrariness. In Chomsky’s formalism, though, the principles of
abstractness of language structure and the arbitrariness between linguistic structure and
meaning are preserved – and the degree of abstractness is increased.

—It is probably not controversial to pair off linguistic formalism from Chomsky and
cognitive psychology. With regard to the tradition, cognitive psychology cannot be
characterized as continuous in the sense outlined for linguistic formalism. Rather, cognitive.
psychology emerged as an antithesis to behavioural psychology (Chomsky, 1959). These
different conditions in history may shed light on the rather simplistic adoption of linguistic
theory into the cognitive approach, and may probably also explain why the assumptions of
linguistic theory are rarely questioned in cognitive approaches to dyslexia. The formalist
propositions regarding innateness and stimuli do fit extensively with the cognitive opposition
to behaviouristic psychology.