Power defaults (preliminary report)

Abstract

We present a spectrum of default logics, using powerdoma~ns to encode default constraints. The resulting non-monotonic entailment relations all satisfy the law of reasoning by cases. This result is a consequence of two general theorems valid for any Scott domain: the Dichotomy Theorem and the Extension Splitting Theorem. We briefly indicate that for propositional logic, the complexity of entailment is complete for co-NP(3).