Unbounded Dependencies and Coordinate Structure

Abstract

Consider eliminating the transformational component of a generative grammar. In particular, consider the elimination of all movement rules, whether bounded or unbounded, and all rules making reference to identity of indices. Suppose, in fact, that the permitted class of generative grammars constituted a subset of those phrase structure grammars capable only of generating context-free languages. Such a move would have two important metatheoretical consequences, one having to do with learnability, the other with processability. In the first place, we would be imposing a rather dramatic restriction on the class of grammars that the language acquisition device needs to consider as candidates for the language being learned. And in the second place, we would have the beginnings of an explanation for the obvious, but largely ignored, fact that humans process the utterances they hear very rapidly.1 Sentences of a context-free language are provably parsable in a time which is proportional to the cube of the length of the sentence or less (Younger (1967), Earley (1970)). But no such restrictive result holds for the recursive or recursively enumerable sets potentially generable by grammars which include a transformational component.