Temporal unification and the temporal partial order

A description is given of two aspects of integrating a temporal reasoner into PROMPT, a system that solves problems in physical domains. The motion of a temporal partial order is introduced first. This partial order maintains linear inequalities, minima and maxima among timepoints; such relations are needed for reasoning with numeric and symbolic temporal information. The author also presents methods for interfacing this temporal reasoner with an existing inference engine. The combination of these methods with standard unification techniques is called temporal unification; its style of unification maintains a transparent interface between the inference engine and the temporal reasoner. By using the temporal partial order and the technique of temporal unification, PROMPT is capable of symbolic and numeric temporal reasoning at multiple levels of abstraction