Frances L. Johnson and Bharat Bhushan
Johnson and Bhushan are investigating the use of credibility ordering for belief revision and default reasoning in deductively open belief spaces. Credibility ordering (epistemic entrenchment) can be used for automatic belief revision within an ATMS-style belief revision system if one assumption that underlies the contradiction has lower credibility than the other assumptions. The credibilities of propositions may be associated directly with them, or may derive from the credibilities of their sources, thus being applicable to higher-level data fusion.
If assumptions (including domain rules) that have different credibilities underly a contradiction, one may choose to disbelieve the assumption with lower credibility, thus performing belief revision, or one may choose to disbelieve the contradictory implication, thus treating the lower credibility rule as a default rule. We are investigating how credibility ordering may be used for both belief revision and default reasoning in the same system.