  Circumscription and logic programs under the stable model semantics are two
well-known nonmonotonic formalisms. The former has served as a basis of
classical logic based action formalisms, such as the situation calculus, the
event calculus and temporal action logics; the latter has served as a basis of
a family of action languages, such as language A and several of its
descendants. Based on the discovery that circumscription and the stable model
semantics coincide on a class of canonical formulas, we reformulate the
situation calculus and the event calculus in the general theory of stable
models. We also present a translation that turns the reformulations further
into answer set programs, so that efficient answer set solvers can be applied
to compute the situation calculus and the event calculus.
