Regarding the question by Al Vilcius, the most direct correspondence with category theory that I am aware of is in my recent work on the foundations of object-oriented programming using rewriting logic. Two relevant refences are: "Conditional Rewriting Logic as a Unified Model of Concurrency," Theoretical Computer Science, 96, 73-155, 1992. "A Logical Theory of Concurrent Objects and its Realization in the Maude Language," Technical Report SRI-CSL-92-08, Comp. Sci. Lab., SRI International, July 1992. The first paper focuses more on the logic and the categorical foundations but contains also a discussion of object-oriented programming and of other models. The second treats in much more detail the foundations of object-oriented programming. The report can be obtained free of charge by writing or sending email to: Mrs. Judith Burgess Computer Science Laboratory 333 Ravenswood Avenue Menlo Park CA 94025, USA (burgess@csl.sri.com) Jose Meseguer ==============================================================================