Modal Event Calculus in Lolli

This paper introduces two variants of the Event Calculus (EC) with relative timing of events: the Credulous and the Skeptical Event Calculus (CREC and SKEC respectively). A model that takes into account the dynamics of event ordering updates is constructed for EC. In this model, that appears to be a restriction of the usual model for the modal logic S4, CREC and SKEC are proved to be the modal counterparts of EC. It is then shown how a full propositional modal logic based on these calculi can be conveniently and elegantly coded by means of the linear logic programming language Lolli.