The limits of unification

Abstract

Current complex-feature based grammars use a single procedure---unification---for a multitude of purposes, among them, enforcing formal agreement between purely syntactic features. This paper presents evidence from several natural languages that unification---variable-matching combined with variable substitution---is the wrong mechanism for effecting agreement. The view of grammar developed here is one in which unification is used for semantic interpretation, while purely formal agreement involves only a check for non-distinctness---i.e. variable-matching without variable substitution.