The following talk will be held in the Salle de Conference of LIX at 14h on 20 March 2012.

*An Intuitionistic Logic for Sequential Control*

*by Chuck Liang*

We introduce the propositional logic ICL for “Intuitionistic Control Logic”, which adds to intuitionistic logic elements of classical reasoning without collapsing it into classical logic. As in linear logic, ICL contains two constants for false. However, the semantics of this logic is based on those of intuitionistic logic. Kripke models are defined for this logic, which are then translated into algebraic and categorical representations. In each case the semantics fit inside intuitionistic frameworks (Heyting algebras and cartesian closed categories). We define a sequent calculus and prove cut-elimination. We then formulate a natural deduction proof system with a variation on the lambda-mu calculus that gives a direct, computational interpretation of contraction. This system satisfies the expected properties of confluence and strong normalization. It shows that ICL is fully capable of typing programming language control constructs such as call/cc while maintaining intuitionistic implication as a genuine connective. We then propose to give a more computationally meaningful interpretation of disjunction in this system.