Control (linguistics) - Representing Control

Representing Control

Theoretical linguistics posits the existence of the null pronoun PRO as the theoretical basis for the analysis of control structures. The null pronoun PRO is an element that impacts a sentence in a similar manner to how a normal pronoun impacts a sentence, but the null pronoun is unaudible. The null PRO is added to the controlled predicate, where it occupies the position that one would typically associate with an overt subject (if one were present). The following trees illustrate PRO in both constituency-based structures of phrase structure grammars and dependency-based structures of dependency grammars:

The constituency-based trees are the a-trees on the left, and the dependency-based trees the b-trees on the right. Certainly aspects of these trees - especially of the constituency trees - can be disputed. In the current context, the trees are intended merely to suggest by way of illustration how control and PRO are conceived of. The indices are a common means of identifying the controller of PRO and the controlled predicate, and the orange arrows indicate further the control relation. In a sense, the controller assigns its index to PRO, which identifies the argument that is understood as the subject of the controlled predicate.

A (constituency-based) X-bar theoretic tree that is consistent with the standard GB-type analysis is given next:

The details of this tree are, again, not so important. What is important is that by positing the existence of the null subject PRO, the theoretical analysis of control constructions gains a useful tool that can help uncover important traits of control constructions.