Qualitative Temporal Reasoning about Vague Events

The temporal boundaries of many real–world events are inherently vague. In this paper, we discuss the problem of qualitative temporal reasoning about such vague events. We show that several interesting reasoning tasks, such as checking satisfiability, checking entailment, and calculating the best truth value bound, can be reduced to reasoning tasks in a well–known point algebra with disjunctions. Furthermore,we identify a maximal tractable subset of qualitative relations to support efficient reasoning.