A phrase marker is a symbol, or complex token, that is used in the formal study of language (Cook & Newson, 1996). It is a tree-like structure that makes explicit three different characteristics of a sentence: the linear order of words in the sentence, the parts of speech in the sentence (e.g., verbs, nouns), and the constituent structure of the sentence (e.g., that one component of a sentence might be a noun phrase). A phrase marker is generated by the rewrite rules of a context free grammar, such as a sentence node may consist of a noun phrase, auxiliary verb, and verb phrase (S -> NP Aux VP). Phrase markers are themselves manipulated by the transformational rules in a generative grammar, like the move-alpha rule. As a component of generative grammar, they are important because they (and how they are transformed) provide an example of how classical information processing might be related to an important psychological phenomenon (language).
- Cook, V. J., & Newson, M. (1996). Chomsky's universal grammar: An introduction (Second edition). Oxford: Blackwell
(Added October 2009)