The authors describe a logical language called versatile event logic (VEL), and sketch how other languages--such as McCarthy and Hayes’ situation calculus [1], Allen’s interval logic [2], and Kowalski and Sergot’s event calculus [3]--can be represented in it.

The language supports branching time, and borrows Gupta’s treatment of count nouns [4]. The authors disallow infinite variation of a proposition’s truth value during a finite interval (which they call “intermingling”); this restriction has appeared in the interval temporal logic literature (see, for example, Pandya [5]). Some axioms are also proposed, although there is no completeness proof.

While the framework is general, it remains to be seen whether artificial intelligence (AI) researchers will use it.