A Theory of Granularity and its Application to Problems of Polysemy and Underspeci cation of Meaning

Communication using natural language is remarkably e cient, by allowing reuse (through the use of generative devices) of a nite vocabulary to describe a potentially innite set of situations. This vocabulary reuse contributes to words having many related senses (polysemy). Further, meanings can be relatively vague or precise; in other words, varying in their degree of speci cation of meaning. I suggest that these problems can be addressed by developing a knowledge representation which makes explicit the notion of granularity. As the grain size changes, we may fold certain distinctions, or split meanings more nely. In this paper, I formalize a theory of granularity and demonstrate how it can be applied to problems of meaning representation. Such a theory requires a world model which provides a rich sortal di erentiation of entities based on the distinctions made by natural language, including the representation of meronymic structure and rei-cation. Granularity will be represented in terms of structural operations de ned as abstractions. I illustrate how this applies to problems of polysemy and vagueness in nominalizations, where splitting and folding of meanings are particularly evident.