A Sequent Calculus for Intuitionistic Default Logic

Current research on non-monotonic reasoning shows growing interest on implementation details, so the need for concrete calculi formalizing non-monotonic logics is clearly recognized. On the other hand, there is also an increased number of works combining intuitionistic logic with various kinds of non-monotonic formalisms. As a case in point, intuitionistic versions of both default and autoepistemic logics have been proposed, and tight connections between intuitionistic logic and logic programs (or deductive databases) using hypothetical inferences have been established. In this paper, we present a sequent calculus for default reasoning in the style of Bonatti with intuitionistic logic as the underlying logical structure. In contrast to other proposals, Bonatti's technique allows a very simple and intuitive speciication of the calculus, making it an ideal tool for implementation purposes.