Chronological Ignorance: Time, Nonmonotonicity, Necessity and Causal Theories

Concerned with the problem of reasoning efficiently about change within a formal system, we identify the initiution problem. The solution to it which we offer, called the logic of chronological ignorance, combines temporal logic, nor-monotonic logic, and the modal logic of necessity. We identify a class of theories, called causal theories, which have elegant model-theoretic and complexity properties in the new logic.