Representing Absolute Time Expressions with Vagueness, Indeterminacy, and Different Granularities

Absolute time expressions axe related to the specification of the position of either a time point or an interval on the time axis. The data model we sketch in this paper allows us to represent in a seamless way expressions with indeterminacy ("between 6 and 6:30 p.m., August 10, 1997", "from 5-5:45 to 8-8:15 p.m., January 11, 2000"), with different granularities ("on December 19, 1998", "at 2:30 p.m., September 23, 1998"), with vagueness ("at the end of January 1998"), and with granularities/indeterminacy/vagueness together ("from March to the beginning of May, 1998", "from the end of June 1999 for 34-45 days"). Our data model is mainly based on the integration of different approaches: the framework proposed by Bettini and colleagues for temporal granularities has been suitably merged with the representation of temporal (fuzzy) knowledge by the possibility theory. To deal with uncertainty from temporal relationships, the data model has been based on a multivalued logics.