A sequent calculus for circumscription

. In this paper, we introduce a sequent calculus CIRC for propositional Circumscription. This work is part of a larger project, aiming at a uniform proof-theoretic reconstruction of the major families of non-monotonic logics. Among the novelties of the calculus, we mention that CIRC is analytic and comprises an axiomatic rejection method, which allows for a fully detailed formalization of the nonmonotonic aspects of inference. 1 Introduction Non-monotonic logics play a fundamental role in knowledge representation and commonsense reasoning, as well as in the theory of programming languages. The semantic and algorithmic aspects of non-monotonic reasoning have been extensively investigated (e.g. see [21, 25, 12, 16, 17, 8, 28, 33, 24] and [29, 26, 2, 5, 35, 1]). On the other hand, the proof-theoretic aspects are not yet completely understood. The fundamental papers by Gabbay [13] , Makinson [23] and Kraus, Lehmann and Magidor [18] , focus their attention on general properties of ..