In X-bar theory, a functional projection is the projection of a functional head, such as COMP (CP), INFL (IP), or Det (DP). The underlying assumption is that, like the lexical heads N, A, V and P, functional heads have a syntactic projection as dictated by X-bar theory.
A fundamental question is whether there is a limit to the number of functional categories. It seems reasonable to assume that their projection is in some sense parasitic on, or an extension of, a lexical projection.
- Abney, S. 1987. The English Noun Phrase in its Sentential Aspect, Unpublished Diss MIT.
- Chomsky, N. 1986b. Barriers, MIT Press, Cambridge, Mass.
- Ouhalla, J. 1990. Functional categories and parametric variation, diss. UCL.
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