The Ramification Problem in Temporal Databases: Concurrent Execution with Conflicting Constraints

In this paper we study the ramification problem in the setting of temporal databases. Standard solutions from the literature on reasoning about action are inadequate because they rely on the assumptions that fluents persist and actions have effects on the subsequent situation only. We provide a solution based on an extension of the situation calculus and the work of McCain and Turner. More specifically, we study the case where there are conflicting effects of concurrently executing actions and we distinguish between hard and soft integrity constraints.