C-command

In syntax, C-command is a binary relation between nodes in a tree structure which is defined as follows:

 (i) Node A c-commands node B iff

    a  A =/= B,
    b  A does not dominate B and B does not dominate A, and
    c  every X that dominates A also dominates B.

  (ii)	 (tree structure)
             X2

/ \ A X₁

                  / \

B C

In (ii) A c-commands B since A =/= B (cf. (i)a), A does not dominate B, nor does B dominate A (cf. (i)b); and the node which dominates A, X2, also dominates B (cf. (i)c). X1 in (ii) is not relevant to (i)c: although it dominates B, it does not dominate A.

For the possible choices of X in (i)c several options have been proposed. The first option is to interpret X as any branching node. Under this interpretation A c-commands B iff (ia) and (ib) are met and the first branching node dominating A also dominates B. This structural relation is sometimes referred to as strict c-command.

An alternative option for the possible values of X in (i)c is to count only maximal projections. Under this interpretation A is said to m-command B.

Examples

In (iii) V c-commands NP the book, but not the PP in the store: when we start from V and move upwards, the first branching node we reach is V'₁. This node dominates the NP the book and it does not dominate the PP in the store. By the same token the P in c-commands the NP the store; it does not c-command the V'₁ buy the book, nor the V and the NP contained in V'₁, because the first branching node dominating P does not dominate V'₁.

 (iii)	 (tree structure)
       VP

| V'₂ |\ | PP | \ | P' | |\ V'₁ | \ |\ P NP | \ | | | \ in the store | \ V NP

  	 |   |	

buy the book

V in (iii) m-commands both the NP the book and the PP in the store and what is contained in them. P does not m-command V, because there is a maximal projection PP which dominates P and does not dominate V, nor the NP the book.

Comments

The minimal phrase which contains a c- or m-commanding element A is the c- or m-command domain of that element. The notion 'minimal phrase' is defined according to the interpretation of X in the definition in (i). Thus, if A m-commands B, the minimal phrase containing A is labeled XP. The m-command domain, then, is the smallest maximal projection containing A. In (iii) PP, not VP, is the m-command domain of P, since PP is the smallest maximal projection in which P appears. If A c-commands B the minimal phrase is the first branching node dominating A. Thus, V'₁ in (iii) is the c-command domain of V. The c-command domain of an element must be a constituent, given that it consists of all the material dominated by one node; hence the term c(onstituent)-command. Other proposals restrict X to lexical categories, major categories. The notion c-command plays a role in the definitions of government, binding, and scope.

Link

Utrecht Lexicon of Linguistics

References

• Aoun, Y. & Sportiche, D. 1983. On the formal theory of Government. The Linguistic Review 2/3, 211-236.
• Chomsky, Noam A. 1981. Lectures on Government and Binding. Dordrecht:Foris.
• Chomsky, Noam A. 1986. Knowledge of language: its nature, origin and use. Praeger, New York.
• Chomsky, Noam A. 1986b. Barriers. MIT Press, Cambridge, Mass.
• Chomsky, Noam A. 1993. A Minimalist Program for Linguistic Theory. MIT occasional papers in linguistics, 1-67.
• Reinhart, T. 1976. The syntactic domain of anaphora. Diss, MIT.