When X takes a complement, X plus its complements forms a phrase.
By extension of this concept, X forms a phrase when it is intransitive.
X - XP forms a projection of X. The minimal projection
of X is the head, X. The maximum projection of X is the
XP in the projection that is not dominated by XP in the same projection.
The last sentence in the above paragraph is intended to cover adjunction. If Y is adjoined to XP, a new node XP is created such that it immediately dominates Y and XP. Thus the projection of X may grow as long as some node is adjoined to XP, or in some case to X.
The concept of the projection of X is useful in defining c-command. Wean we say X c-commands a node YP, we really mean that the maximal projection of X c-commands YP.
In the following structure, the oval encircles the projection of X.
(1)
The notion the extended projection of X is useful in conjunction
constructions. If XP-1 and XP-2 are conjoined, they are dominated
by XP-1+2. The node XP-1+2 forms the extended projection of X-1
and X-2.
Consider the following example:
(2). The dog and the cat saw themselves in the mirror.
Neither the maximal projection the dog nor the cat alone can function as the antecedent of themselves alone. Only the extended projection of the dog and the cat can function as the antecedent.
(3).
