Definition

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

$S \to NP \quad VP$
$NP \to Det \quad N1$
$N1 \to (AP) \quad N1 \quad (PP)$

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, PP

Associated with phrase structure rules is a famous example of a grammatically correct sentence. In Linguistics, a sentence is a grammatical unit of one or more words bearing minimal syntactic relation to the words that precede or follow it often preceded and followed In grammatical theory, a noun phrase (abbreviated NP) is a Phrase whose head is a Noun or a Pronoun, optionally accompanied In Linguistics, a verb phrase or VP is a syntactic structure composed of the predicative elements of a sentence and functions An adjectival phrase or adjective phrase (AP is a Phrase with an Adjective as its head. An adpositional phrase is a Linguistics term that includes (a prepositional phrase(s (which are usually found in head-first languages like English) and The sentence was constructed by Noam Chomsky as an illustration that syntactically but not semantically correct sentences are possible. Avram Noam Chomsky (noʊm ˈtʃɑmski born December 7 1928 is an American linguist, Philosopher, cognitive scientist, Political

Colorless green ideas sleep furiously can be diagrammed as a phrase tree, as below:

where S represents a grammatical sentence. " Colorless green ideas sleep furiously " is a sentence composed by Noam Chomsky in 1957 as an example of a sentence whose Grammar is correct The theory of antisymmetry proposed in the early '90s by Richard Kayne is an attempt to derive phrase structure from a single axiom. Antisymmetry is a theory of syntactic linearization presented in Richard Kayne 's 1994 monograph The Antisymmetry of Syntax.

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. In Mathematics, Semantics, and Philosophy of language, the Principle of Compositionality is the principle that the meaning of a complex expression is determined Semantics is the study of meaning in communication The word derives from Greek σημαντικός ( semantikos) "significant" from

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: