Almost Definite Causal Theories

The language of nonmonotonic causal theories, defined by Norman McCain and Hudson Turner, is an important formalism for representing properties of actions. For causal theories of a special kind, called definite, a simple translation into the language of logic programs under the answer set semantics is available. In this paper we define a similar translation for causal theories of a more general form, called almost definite. Such theories can be used, for instance, to characterize the transitive closure of a binary relation. The new translation leads to an implementation of a subclass of almost definite causal theories that employs the answer set solver smodels as the search engine.