Proceedings of the Annual Meeting of the Cognitive Science Society

We describe harmonic grammar, a connectionist-based approach to formal theories of linguistic well-formedness. The general approach can be applied to various kinds of linguistic well-formedness, e.g., phonological and syntactic. Here, we address a syntactic problem: unaccusativity. Harmonic grammar is a two-lcvcl theory, involving a distributed, lower level connectionist network whose relevant aggregate computational behavior is described by a local, higher level network. The central hypothesis is that the connectionist well-formedness measure called "harmony"^ can be used to model linguistic well-formedness; what is crucial about the relation between the lower and higher level networks is that there is a harmony-preserving mapping between them: they are isoharmonic (at least approximately). A companion paper (Legendre, Miyata, & Smolensky, 1990; henceforth "LMS2") describes the theoretical basis for the two level approach, starting from general connectionist principles. In this paper, we discuss the problem of unaccusativity, give a high level characterization of harmonic syntax, and present a higher level network to account for unaccusativity data in French. W e interpret this network as a fragment of the grammar and lexicon of French expressed in "soft rules." Of the 760 sentence types represented in our data, the network correctly predicts the acceptability in all but two cases. This coverage of real, problematic syntactic data greatly exceeds that of any other formal account of unaccusativity of which we are aware.