Primitives and Units for Time Specification

We work in a calculus of intervals, formulated by James Allen for convex intervals, and by ourselves for unions of convex intervals [AZZ2,Lad.Z]. W e investigate the primitive relations and operations needed for implementing such calculi in a system which includes some set theory, and which allows the assertional definition of operators in Horn clause fashion. We indicate how standard temporal logic may be rephrased in the interval calculus, and present a formalisation of a system of time units in the interval framework. We are implementing the primitives in the REF IN ETM system’.