This is the first-year funding of a three-year continuing award IRI-9213894. In previous research, an approach to the formal study of language, Harmonic Grammar, relies on a novel means of integrating connectionist and symbolic computation. The current research studies extensions of this approach, concerning formal grammars of natural languages and grammars of formal languages. Specifically, the previous work is extended: to encompass recursive, fully distributed connectionist representations; to develop an explicit symbolic programming language to characterize the computations over these representations carried out by a new class of connectionist networks; to study the expressive power of Harmonic Grammar to describe formal languages, starting with a study of context-free languages; to analyze the properties of connectionist networks that lead to a recursive, embedding- invariant well-formedness (Harmony) function; to test the ability of Harmonic Grammar to deal with linguistic problems crucially involving embedding; to assess the effectiveness of our fully distributed representations for encoding the features of syntactic/semantic structural roles in linguistic representations; to extend the theory to incorporate the symbolic computational notion of unification, and to apply it to unification-based approaches to natural language grammar; to study the effectiveness and temporal behavior of connectionist parsers that implement both the numerical and nonnumerical formalizations of Harmonic Grammar; and to extend recent work on connectionist learning of symbolic rule systems to the particular case of Harmonic Grammar.//
