Combining time points and time intervals in a hybrid knowledge-representation formalism

In the paper, I illustrate an approach for combining time points and time intervals. I propose a uniform definition of time points and time intervals and of the temporal relationships between them, and I describe an integrated temporal reasoner which operates on such a representation. Such a reasoner allows one, among other things, to subdivide an intractable problem (constraint propagation in the general case, in which temporal relations between time points, between time points and time intervals and between time intervals are considered at the same time) into (a possibly intractable number of) smaller tractable subproblems (constraint propagation between time points), and adopts a general heuristic in order to improve efficiency. The paper shows how such an approach has been developed by adopting BACK, a standard Hybrid Knowledge Representation formalism.