Etude polarisée du système L

Herbelin coined the name ``System L'' to refer to syntactical quotients of sequent calculi, in which two classes of terms interact in commands, in the manner of Curien's and Herbelin's lambda-bar-mu-mu-tilde calculus or Wadler's dual calculus. This paper introduces a system L that has constructs for all connectives of second order linear logic, and that shifts focus from the old code/environment interaction to a game between positives and negatives. L provides quotients for major second order sequent calculi, in their right-hand-side-sequents formulation as well as their two-sided-sequents formulation, namely LL, LK and LLP. The logician reader will appreciate the unifying framework for the study of sequent calculi it claims to be, whereas the computer scientist reader will appreciate the fact that it is a step toward Herbelin's project of rebuilding a theory of computation that puts ``call by name'' and ``call by value'' on an equal footing --- in particular is L involved with respect to reduction strategies, to wit that a cut elimination protocol that enjoys the Curch-Rosser property seems to stand out, and it allows to mix lazy and eager aspects. The principal tool for the study of this system is classical realizability, a consequence being that this tool is now extended to call by value

Kripke Models for Classical Logic

We introduce a notion of Kripke model for classical logic for which we constructively prove soundness and cut-free completeness. We discuss the novelty of the notion and its potential applications

Etude polarisée du système L

Herbelin coined the name ``System L'' to refer to syntactical quotients of sequent calculi, in which two classes of terms interact in commands, in the manner of Curien's and Herbelin's lambda-bar-mu-mu-tilde calculus or Wadler's dual calculus. This paper introduces a system L that has constructs for all connectives of second order linear logic, and that shifts focus from the old code/environment interaction to a game between positives and negatives. L provides quotients for major second order sequent calculi, in their right-hand-side-sequents formulation as well as their two-sided-sequents formulation, namely LL, LK and LLP. The logician reader will appreciate the unifying framework for the study of sequent calculi it claims to be, whereas the computer scientist reader will appreciate the fact that it is a step toward Herbelin's project of rebuilding a theory of computation that puts ``call by name'' and ``call by value'' on an equal footing --- in particular is L involved with respect to reduction strategies, to wit that a cut elimination protocol that enjoys the Curch-Rosser property seems to stand out, and it allows to mix lazy and eager aspects. The principal tool for the study of this system is classical realizability, a consequence being that this tool is now extended to call by value

From Proof Nets to the Free *-Autonomous Category

In the first part of this paper we present a theory of proof nets for full multiplicative linear logic, including the two units. It naturally extends the well-known theory of unit-free multiplicative proof nets. A linking is no longer a set of axiom links but a tree in which the axiom links are subtrees. These trees will be identified according to an equivalence relation based on a simple form of graph rewriting. We show the standard results of sequentialization and strong normalization of cut elimination. In the second part of the paper we show that the identifications enforced on proofs are such that the class of two-conclusion proof nets defines the free *-autonomous category.Comment: LaTeX, 44 pages, final version for LMCS; v2: updated bibliograph

A System of Interaction and Structure

This paper introduces a logical system, called BV, which extends multiplicative linear logic by a non-commutative self-dual logical operator. This extension is particularly challenging for the sequent calculus, and so far it is not achieved therein. It becomes very natural in a new formalism, called the calculus of structures, which is the main contribution of this work. Structures are formulae submitted to certain equational laws typical of sequents. The calculus of structures is obtained by generalising the sequent calculus in such a way that a new top-down symmetry of derivations is observed, and it employs inference rules that rewrite inside structures at any depth. These properties, in addition to allow the design of BV, yield a modular proof of cut elimination.Comment: This is the authoritative version of the article, with readable pictures, in colour, also available at . (The published version contains errors introduced by the editorial processing.) Web site for Deep Inference and the Calculus of Structures at <http://alessio.guglielmi.name/res/cos