WHY TRICATEGORIES

We outline a logical framework, based on the theory of categories with extra structure, for logics that arise in computer science. We list many representative examples of structures that have arisen, then we classify them in terms of equational, and the more general essentially algebraic, structure. In both cases, we outline the main results and their significance for the logical framework. This study gives rise to coherence questions. We explain the issues, and then outline the category theoretic concepts, such as tricategories, that arise in resolving the coherence problems. (C) 1995 Academic Press, Inc.