Probabilistic Reasoning about Actions in Nonmonotonic Causal Theories
  We present the language {m P}{cal C}+ for probabilistic reasoning about
actions, which is a generalization of the action language {cal C}+ that allows
to deal with probabilistic as well as nondeterministic effects of actions. We
define a formal semantics of {m P}{cal C}+ in terms of probabilistic
transitions between sets of states. Using a concept of a history and its belief
state, we then show how several important problems in reasoning about actions
can be concisely formulated in our formalism.
