Phrase-structure rules were used in early transformational grammar (TGG) to describe a given language's syntax. They were used to break a natural language sentence down into its constituent parts (also known as syntactic categories) namely phrasal categories and lexical categories (aka parts of speech). Phrasal categories include the noun phrase, verb phrase, and prepositional phrase; lexical categories include noun, verb, adjective, adverb, and many others. Phrase structure rules were not an invention of TGG; rather, early TGG's defining characteristics were those systems which it had in addition to phrase structure rules (the most obvious example being transformations; see the page transformational grammar for an overview of the development of TGG.) A grammar which uses phrase structure rules is called a phrase structure grammar. Transformational grammar is a broad term describing grammars (almost exclusively those of natural languages) which have been developed in a Chomskian tradition. ... Syntax, originating from the Greek words συν (syn, meaning co- or together) and τάξις (táxis, meaning sequence, order, arrangement), can in linguistics be described as the study of the rules, or patterned relations that govern the way the words in a sentence come together. ... A syntactic category is either a phrasal category, such as noun phrase or verb phrase, which can be decomposed into smaller syntactic categories, or a lexical category, such as noun or verb, which cannot be further decomposed. ... In grammar, a part of speech or word class is defined as the role that a word (or sometimes a phrase) plays in a sentence. ... In linguistics, a noun phrase is a phrase whose Head is a noun. ... A verb phrase (VP) is a phrase whose head is a verb. ... A prepositional phrase (PP) is a linguistic term for a phrase whose head is a preposition. ... A noun, or noun substantive, is a part of speech (a word or phrase) which can co-occur with (in)definite articles and attributive adjectives, and function as the head of a noun phrase. ... A verb is a part of speech that usually denotes action (bring, read), occurrence (decompose, glitter), or a state of being (exist, stand). Depending on the language, a verb may vary in form according to many factors, possibly including its tense, aspect, mood and voice. ... An adjective is a part of speech which modifies a noun, usually describing it or making its meaning more specific. ... An adverb is a part of speech-class. ... Transformational grammar is a broad term describing grammars (almost exclusively those of natural languages) which have been developed in a Chomskian tradition. ...

Definition

Phrase structure rules are usually of the form , meaning that the constituent A is separated into the two subconstituents B and C. Some examples are:

The first rule reads: An S consists of an NP followed by a VP. This means A sentence consists of a noun phrase followed by a verb phrase. The next one: A noun phrase consists of a determiner followed by a noun.

Further explanations of the constituents: S, Det, NP, VP, AP In linguistics, a sentence is a unit of language, characterised in most languages by the presence of a finite verb. ... Determiners are words which quantify or identify nouns. ... In linguistics, a noun phrase is a phrase whose Head is a noun. ... A verb phrase (VP) is a phrase whose head is a verb. ... An adjectival phrase is a phrase with an adjective as its head (e. ...

Associated with phrase structure rules is a famous example of a grammatically correct sentence. The sentence was constructed by Noam Chomsky as an illustration that syntactically but not semantically correct sentences are possible. Noam Chomsky Avram Noam Chomsky (b. ...

Colorless green ideas sleep furiously can be diagrammed as a phrase tree, as below: Where S represents a grammatical sentence. ...

where S represents a grammatical sentence. Phrase diagram for Colorless green ideas sleep furiously. ...

Alternative approaches

A number of theories of grammar dispense with the notion of phrase structure rules and operate with the notion of schema instead. Here phrase structures are not derived from rules that combine words, but from the specification or instantiation of syntactic schemata or configurations, often expressing some kind of semantic content independently of the specific words that appear in them. This approach is essentially equivalent to a system of phrase structure rules combined with a noncompositional semantic theory, since grammatical formalisms based on rewriting rules are generally equivalent in power to those based on substitution into schemata. The word schema comes from the Greek word σχήμα (skhēma) that means shape or more generally plan. ... The Principle of Compositionality in semantics is the principle that the meaning of a complex expression is determined by the meanings of its constituent expressions and the rules used to combine them. ... In the main, semantics (from the Greek and in greek letters σημαντικός or in latin letters semantikós, or significant meaning, derived from sema, sign) is the study of meaning, in some sense of that term. ...

So, in this type of approach, instead of being derived from the application of a number of phrase structure rules, the sentence "colorless green ideas sleep furiously" would be generated by filling the words into the slots of a schema having the following structure:

(NP(ADJ N) VP(V) AP(ADV))

And which would express the following conceptual content

X DOES Y IN THE MANNER OF Z

Though they are noncompositional, such models are monotonic. This approach is highly developed within Construction grammar, and has had some influence in Head-Driven Phrase Structure Grammar and Lexical functional grammar. In mathematics, functions between ordered sets are monotonic (or monotone) if they preserve the given order. ... The term construction grammar (CxG) covers a family of theories, or models, of grammar that are based on the idea that the primary unit of grammar is the grammatical construction rather than the atomic syntactic unit and the rule that combines atomic units, and that the grammar of a language... The Head-driven phrase structure grammar (HPSG) is a non-derivational generative grammar theory developed by Carl Pollard and Ivan Sag (1985). ... Lexical functional grammar (LFG) is a reaction to the direction research in the area of transformational grammar began to take in the 1970s. ...

See also

• Context free grammar
• Phrase structure grammar