Default Reasoning and Belief Revision：A Syntax—Independent Approach

AsanimportantvariantofReiter'sdefaultlogic.Poole(1988)developedanonmonotonicreasoningframeworkintheclassicalfirst-orderlanguage,BrewkaandNebelextendedPoole'sapproachinordertoenablearepresentationofprioritiesbetweendefaults.Inthispaperageneralframeworkfordefaultreasoningispresented,whichcanbeviewedasageneralizationofthethreeapproachesabove.Itisprovedthatthesyntax-independentdefaultreasoninginthisframeworkisidenticaltothegeneralbeliefrevisionoperationintroducedbyZhangetal.(1997).Thisesultprovidesasolutiontotheproblemwhetherthereisacorrespondencebetweenbeliefrevisionanddefaultlogicfortheinfinitecase.Asaby-product,ananswertothethequestion,raisedbyMankinsonandGaerdenfors(1991),isalsogivenaboutwhetherthereisacounterpartcontracitoninnonmonotoniclogic.