ASSIGNED-TIME_RANGE returns a time range to which a job is assigned.
(Slot-Cardinality ?Class Assigned-Time-Range 1)
(<=> (Temporally-Fixed-Job-Class ?Class)
(And (Class ?Class)
(Subclass-Of ?Class Job)
(Slot-Cardinality ?Class Assigned-Time-Range 1)))
(=> (Assigned-Time-Range $X $Y) (Jat-Time-Range $Y))
(=> (Assigned-Time-Range $X $Y) (Job $X))