n.(CF-rule) (more fully, context-free phrase structure rule, or CF-PS-rule) 1. A rewrite rule which expands exactly one category into an ordered string of zero or more categories and for the application of which no environment is specified. Examples are the rules NPPron, SNP VP, VP V NP NP and NPe. 2. In the writings of Noam Chomsky and his associates, a rewrite rule which expands exactly one category into an ordered string of one or more categories and for the application of which no environment is specified.
This definition differs from the previous one in excluding null productions like the rule NPe. Cf. context-sensitive rule,immediate-dominance rule. NOTE: Chomsky’s definition has the benefit of historical priority, but it is clear that the practice of the American structuralists which Chomsky was proposing to formalize actually requires the first definition; in any case, the first definition is now almost universally preferred by those linguists who take phrase structure rules seriously, following Bar-Hillel et al. (1961). See Manaster-Ramer and Kac (1990) for discussion.
This is the complete article, containing 173 words
(approx. 1 page at 300 words per page).
Pron, S
NP VP, VP 
V NP NP and NP
e. 2. In the writings of Noam Chomsky and his associates, a rewrite rule which expands exactly one category into an ordered string of one or more categories and for the application of which no environment is specified. 
e. Cf. 
