R. Li and J. Carmo, "On completeness of a positional
interval logic with equality, overlap and subinterval relations", 
<i> Journal of the IGPL (Interest Group on
Propositional and Predicate Logic)</I>, 1995, Vol. 3, No. 5, pp. 765--790.
<P>A new logic for reasoning about time intervals is presented and proven
to be <I> complete</I> in the standard logical sense: if a statement $S$
is true in all possible situations, then $S$ can be deduced from the
axioms of this logic by using its deduction rules. This result can be
used to design a computer system that would automatically check
whether a given statement about time intervals is true or not.