A GENERAL FRAMEWORK FOR TIME GRANULARITY AND ITS APPLICATION TO TEMPORAL REASONING

This paper presents a general framework to define time granularity sys tems. We identify the main dimensions along which different systems ca n be characterized, and investigate the formal relationships among gra nularities in these systems. The paper also introduces the notion of a network of temporal constraints with (multiple) granularities emphasi zing the semantic and computational differences from constraint networ ks with a single granularity. Consistency of networks with multiple gr anularities is shown to be NP-hard in general and approximate solution s for this problem and for the minimal network problem are proposed.