On Default Handling: Consistency Before and After.

Abstract

In common sense reasoning it is important to be able to handle conflicting data. We discuss this issue specifically in the context of default reasoning. We contrast two choices: either to constantly monitor the reasoning system in an effort to preserve consistency, or to allow inconsistencies to arise and then (try to) restore a semblance of order. That these are computationally virtually the same is granted; but there are other rather important distinctions between them bearing on default reasoning.