This paper extends earlier work by its authors on formal aspects of the processes of contracting a theory to eliminate a proposition and revising a theory to introduce a proposition. In the course of… (More)

We explain the raison d’être and basic ideas of input/output logic, sketching the central elements with pointers to other publications for detailed developments. The motivation comes from the logic… (More)

We show how nonmonotonic inferences may elegantly be interpreted in terms of underlying expectations . The fundamental idea is that when we reason, we make use of not only the information that we… (More)

This paper is concerned with formal aspects of the logic of theory change, :and in particular with the process of shrinking or contracting a theory to eliminate a proposition. It continues work in… (More)

In a previous paper we developed a general theory of input/output logics. These are operations resembling inference, but where inputs need not be included among outputs, and outputs need not be… (More)

The splitting theorem says that any set of formulae has a finest representation as a family of letter-disjoint sets. Parikh formulated this for classical propositional logic, proved it in the finite… (More)

We discuss the rather special status of the postulate of “recovery” among the six basic postulates for theory contraction as formulated and studied by Alchourron, Gardenfors and the author. Our… (More)