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:
-
- 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:
“Beauty, like all other qualities presented to human experience, is relative; and the definition of it becomes unmeaning and useless in proportion to its abstractness. To define beauty not in the most abstract, but in the most concrete terms possible, not to find a universal formula for it, but the formula which expresses most adequately this or that special manifestation of it, is the aim of the true student of aesthetics.”
—Walter Pater (1839–1894)
“According to our social pyramid, all men who feel displaced racially, culturally, and/or because of economic hardships will turn on those whom they feel they can order and humiliate, usually women, children, and animals—just as they have been ordered and humiliated by those privileged few who are in power. However, this definition does not explain why there are privileged men who behave this way toward women.”
—Ana Castillo (b. 1953)
“The physicians say, they are not materialists; but they are:MSpirit is matter reduced to an extreme thinness: O so thin!—But the definition of spiritual should be, that which is its own evidence. What notions do they attach to love! what to religion! One would not willingly pronounce these words in their hearing, and give them the occasion to profane them.”
—Ralph Waldo Emerson (1803–1882)