This is a proposal for renewed support of a project in linguistic theory which has proven exceedingly productive, with results of both theoretical and practical importance. The researcher is continuing to investigate the possibilities and problems of an explicit theory of linguistic syntax and semantics which operates on a single level of representation, with rules with strictly defined and restricted formal properties. Most theoreticians have found it necessary to postulate two or more levels of representation, and rules of a variety of formal types, in order to account for the data observed in natural language. The theory proposed here, by being more restricted in its scope and power, makes much stronger and more interesting claims about the underlying nature of language, and to the extent that it can be shown to be valid empirically, it thus constitutes a significant advance in linguistic theory. In order to validate the theory empirically, the investigator must deal satisfactorily with the numerous empirical problems which have led other researchers to postulate more complex theories, and that is the burden of the project proposed here. The project has, as mentioned above, practical import in addition to its empirical interest. The restricted theory being explored permits much faster and more efficient computer processing than more diverse theories do, and to the extent it can handle the data of natural language and produce useful output, it offers the prospect of a major advance in computer systems for natural language processing.
