Permissive belief revision using default logic

An important aspect of commonsense reasoning is the ability to revise our beliefs, i.e., change our beliefs, e.g. to get rid of a contradiction. Most existing belief revision theories consider beliefs to be atomic, i.e., they either choose to keep that belief or to abandon it. We believe this is a big handicap since one belief may incorporate several "sub-beliefs" not necessarily all true or all false. The idea behind permissive revision is to take the abandoned beliefs, weaken them, and add the weakened beliefs to the result of classical (in the sense of non-permissive) revision. So, the advantage of permissive revision over classical revision is that in some situations it allows us to keep more information. In this paper we modify a previous permissive belief revision theory to use Default Logic, as its underlying logic.