INTEGRATING CALENDAR DATES AND QUALITATIVE TEMPORAL CONSTRAINTS IN THE TREATMENT OF PERIODIC EVENTS

The paper describes a framework for representing and reasoning with pe riodic events. In particular, it proposes a temporal formalism which d eals with both 1) quantitative information concerning the frame of tim e (e.g., between 1990 and 1993) and the user-defined calendar-dates (e .g., on the first Mondays of April) in which periodic events are locat ed and 2) the qualitative relations between periodic events (e.g., Sam visits the branch office X01 before going to his office). The meaning of the temporal specifications in our formalism is described in logic al terms. The paper defines the basic operations of inversion, interse ction and composition of temporal specifications. These operations are correct (with respect to the logical definition of the specifications ) and do not lose information. Finally, the paper also describes a cor rect algorithm which takes advantage of these operations for performin g temporal reasoning, and analyses its complexity. An application of t he temporal framework to the scheduling in an office is shown in an ex ample.