Definition
Phrase structure rules are usually of the following form:
meaning that the constituent is separated into the two subconstituents and . Some further examples for English are as follows:
The first rule reads: An S (sentence) consists of an NP (noun phrase) followed by a VP (verb phrase). The second rule reads: A noun phrase consists of a Det (determiner) followed by an N (noun). Some further categories are listed here: AP (adjective phrase), AdvP (adverb phrase), PP (prepositional phrase), etc. Applying the phrase structure rules in a neutral manner, it is possible to generate many proper sentences of English. But it is also quite possible that the rules generate syntactically correct but semantically nonsensical sentences. The following example sentence is notorious in this regard, since it is complete nonsense, even though it is syntactically correct:
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- Colorless green ideas sleep furiously
This sentence was constructed by Noam Chomsky as an illustration that phrase structure rules are capable of generating syntactically correct but semantically incorrect sentences. Phrase structure rules break sentences down into their constituent parts. These constituents are often represented as tree structures. The tree for Chomsky's famous sentence can be rendered as follows:
A constituent is any word or combination of words that is dominated by a single node. Thus each individual word is a constituent. Further, the subject NP Colorless green ideas, the minor NP green ideas, and the VP sleep furiously are constituents. Phrase structure rules and the tree structures that are associated with them are a form of immediate constituent analysis.
Read more about this topic: Phrase Structure Rules
Famous quotes containing the word definition:
“The man who knows governments most completely is he who troubles himself least about a definition which shall give their essence. Enjoying an intimate acquaintance with all their particularities in turn, he would naturally regard an abstract conception in which these were unified as a thing more misleading than enlightening.”
—William James (1842–1910)
“The very definition of the real becomes: that of which it is possible to give an equivalent reproduction.... The real is not only what can be reproduced, but that which is always already reproduced. The hyperreal.”
—Jean Baudrillard (b. 1929)
“It is very hard to give a just definition of love. The most we can say of it is this: that in the soul, it is a desire to rule; in the spirit, it is a sympathy; and in the body, it is but a hidden and subtle desire to possess—after many mysteries—what one loves.”
—François, Duc De La Rochefoucauld (1613–1680)