Word meaning confronts us, as acutely as anything in syntax, with what Chomsky has called Plato’s problem.1 We know far more about the meaning of almost any word than we could have learned just from our exposure to uses of it. Communication would be unbearably laborious if we did not share with other speakers the ability to generalize the meanings of words in the right ways. As Fodor (1981) notes in arguing for the innateness of lexical semantics, the most we (...) might plausibly have learned about meaning of the verb paint is that it means something like “to cover with paint”. Even if we have only seen this done with a brush, we have no hesitation in applying the verb correctly to novel techniques of painting, such as rolling, spraying, or dipping. But when a vat of paint explodes in a paint factory, covering everyone with paint, or when Vel´. (shrink)

In this paper the Centering model of anaphoraresolution and discourse coherence(Grosz et al. 1983, 1995)is reformulated in terms of Optimality Theory (OT)(Prince and Smolensky 1993). One version of the reformulated modelis proven to be descriptively equivalent to an earlier algorithmicstatement of Centering due to Brennan, Friedman and Pollard(1987). However, the new model is stated declaratively, and makesclearer the status of the various constraints used in the theory. Inthe second part of the paper, the model is extended, demonstratingthe advantages of the (...) OT reformulation, and capturing formallyideas originally described by Grosz, Joshi and Weinstein. Three newapplications of the extended OT Centering model are described:generation of linguistic forms from meanings, the evaluation andoptimization of extended texts, and the interpretation of accentedpronouns. (shrink)