TIME-RANGE denotes a certain period of time. It consists of a start time, an end time. A start time must proceed an end time. Relations between TIME-RANGEs are defined after James Allen's interval relations.
(Tp= (Tp+ (Time-Range.Start-Time ?Time-Range) (Time-Range.Duration ?Time-Range)) (Time-Range.End-Time ?Time-Range))
(=> (Time-Range ?Time-Range) (Tp= (Tp+ (Time-Range.Start-Time ?Time-Range) (Time-Range.Duration ?Time-Range)) (Time-Range.End-Time ?Time-Range))) (=> (Time-Range.Start-Time $X $Y) (Time-Range $X)) (=> (Time-Range.End-Time $X $Y) (Time-Range $X)) (=> (Time-Range.Duration $X $Y) (Time-Range $X))