Encompassing full nonmonotonicity within belief modification activity

Abstract

 In this paper, starting from an analysis of the general activity of belief modification, the concept of full nonmonotonicity is introduced and discussed. Such concept is based on the identification of two different types of nonmonotonicity and includes all the cases of belief modification that may occur in reasoning activity. This distinction cannot be encompassed by the most known nonmonotonic logic formalisms nor by the classical view of conditioning and belief revision axiomatically set up by Gardenfors [9]. A conceptual model able to correctly capture fully nonmonotonic reasoning is discussed: such model includes an explicit representation for the concepts of uncertainty about the applicability of a piece of knowledge and of reasoning attitude. Finally, the issue of formalizing fully nonmonotonic reasoning is discussed and preliminary formalization proposals are introduced.