James M. Crawford, David W. Etherington
The development of a formal logic for reasoning about change has proven to be surprisingly difficult. Furthermore, the logics that have been developed have found surprisingly little application in those fields, such as Qualitative Reasoning, that are concerned with building programs that emulate human common-sense reasoning about change. In this paper, we argue that a basic tenet of qualitative reasoning practice-the separation of modeling and simulation-obviates many of the difficulties faced by previous attempts to formalize reasoning about change. Our analysis helps explain why the QR community has been nonplussed by some of the problems studied in the nonmonotonic reasoning community. Further, the formalism we present provides both the beginnings of a formal foundation for qualitative reasoning, and a framework in which to study a number of open problems in qualitative reasoning.