DTV11 — DTV Issue: Errors in the axioms for ‘time interval1 is before time interval2’

OMG Specification: Date Time Vocabulary

Version: 1.0

Title: Errors in the axioms for ‘time interval1 is before time interval2’

Summary:

In clause 8.2.2, the axioms for ‘time interval1 is before time interval2’ have several problems.

1. In the first axiom, the second Corollary does not follow from the Axiom. if t1 overlaps t2, it is not before or after t2. So: if t1 is before or after t2, it does not overlap t2. But the so-called Corollary (the Axiom of totality) states the converse: if t1 does not overlap t2, then t1 is before or after t2.

2. The SBVR SE statement of irreflexivity demonstrates a disconnect between Structured English and English. Surely the Axiom can be more clearly stated: No time interval is before itself. If the bizarre formulation is required for SBVR, the English expression should be given first.

3. The current “totality” corollary to the Axiom of assymetry is actually just a partition that follows from the assymetry Axiom and the mislabeled axiom above.

Make the second Corollary to the first axiom an axiom in its own right. Add the English version of the irreflexivity axiom as the text of the Axiom proper. There is no problem with the “totality” corollary.