Normalization in Supernatural deduction and in Deduction modulo

Deduction modulo and Supernatural deduction are two extentions of predicate logic with computation rules. Whereas the application of computation rules in deduction modulo is transparent, these rules are used to build non-logical deduction rules in Supernatural deduction. In both cases, adding computation rules may jeopardize proof normalization, but various conditions have been given in both cases, so that normalization is preserved. We prove in this paper that normalization in Supernatural deduction and in Deduction modulo are equivalent, i.e. the set of computation rules for which one system strongly normalizes is the same as the set of computation rules for which the other is

Aspects typés du calcul de réécriture

Stage de DEA. Rapport de stage.Le calcul de réécriture intègre dans un même système le lambda-calcul et la réécriture. Pour cela, les abstractions ne se font plus seulement sur des variables mais sur des motifs. On profite ainsi à la fois des mécanismes d'ordre supérieur du lambda-calcul et de l'expressivité du filtrage de la réécriture. Nous nous intéressons ici au rho-calcul en tant qu'extension du lambda-calcul et nous en étudions les aspects typés, l'objectif étant de mieux comprendre les relations entre ce calcul et les systèmes logiques et ainsi d'étendre l'isomorphisme de Curry-Howard. Notre étude se base sur une généralisation du cube de Barendregt, où les deux abstracteurs lambda et Pi sont unifiés en un seul. Il nous faut aussi tenir compte des nouveaux éléments du rho-calcul. Sous les bonnes conditions, nous parvenons ainsi à prouver la plupart des propriétés habituelles des calculs typés. Cependant, l'unicité du type n'est généralement plus valable, notamment à cause de l'unification des abstracteurs. Nous prouvons que l'unicité reste valide dans les deux systèmes les plus simples

Strong Normalization in two Pure Pattern Type Systems

International audiencePure Pattern Type Systems (P 2 T S ) combine in a unified setting the frameworks and capabilities of rewriting and λ-calculus. Their type systems, adapted from Barendregt's λ-cube, are especially interesting from a logical point of view. Strong normalization, an essential property for logical soundness, had only been conjectured so far: in this paper, we give a positive answer for the simply-typed system and the dependently-typed system. The proof is based on a translation of terms and types from P 2 T S into the λ-calculus. First, we deal with untyped terms, ensuring that reductions are faithfully mimicked in the λ-calculus. For this, we rely on an original encoding of the pattern matching capability of P 2 T S into the System Fω. Then we show how to translate types: the expressive power of System Fω is needed in order to fully reproduce the original typing judgments of P 2 T S . We prove that the encoding is correct with respect to reductions and typing, and we conclude with the strong normalization of simply-typed P 2 T S terms. The strong normalization with dependent types is in turn obtained by an intermediate translation into simply-typed terms

Decidable Type Inference for the Polymorphic Rewriting Calculus

National audienceThe rewriting calculus is a minimal framework embedding lambda calculus and term rewriting systems that allows abstraction on variables and patterns. The rewriting calculus features higher-order functions (from the lambda calculus) and pattern matching (from term rewriting systems). In this paper, we study extensively the decidability of type inference in the second-order rewriting calculus à la Curry

The rho cube : some results, some problems

Held in conjunction with FLOC'02. Colloque avec actes informels avec comité de lecture. internationale.International audienceThe rewriting calculus embeds in a same setting the lambda calculus and the rewriting, by allowing abstraction not only on variables but also on patterns. The higher-order mechanisms of the lambda-calculus and the pattern matching facilities of the rewriting are then both available at the same level. It is worth noticing that the complexity of the calculu breaks the confluence property, so that we need to define appropiate strategies or restrictions, in order to recover it.We choose here to look at the rho-calculus as an extension of the lambda-calculus, and we study the typed aspects. Our study is based upon a generalization of Barendregt's lambda-cube, in which we unify both abstractors lambda and Pi into a single one. We need to deal with the original features of the rho-calculus too: matching power, non-determinism, confluence issues. With proper restrictions, we have proved most of the usual properties for typed calculi: substitution lemma, correctness of types, subject reduction, consistency. Uniqueness of typing is generally no longer valid but we can still prove it for one of the most restrictive systems, rho-> and rho2

Typage et déduction dans le calcul de réécriture

Président : Mariangiola DezaniRapporteurs : Gilles Dowek, Herman GeuversExaminateurs : Adam Cichon, Claude Kirchner, Luigi LiquoriThe rewriting calculus is a lambda-calculus with pattern matching. This thesis is devoted to the study of type systems for this calculus, and to its applications to the domain of deduction.We study two typing paradigms. The first one is inspired by the simply typed lambda-calculus, but it differs from it in the sense that a term may be well-typed without being terminating. Thus, we use it for representing programs and rewriting systems.The second family of type systems we study is adapted from the Pure Type Systems. We show its strong normalization via a translation into a typed lambda-calculus.Finally, we propose two ways of using the rewriting calculus in logic. In the first approach, we use the strongly normalizing systems to define proof terms for deduction modulo. In the second case, we define a generalization of natural deduction and we show that matching is useful in order to represent the rules of this deduction system.Le calcul de réécriture est un lambda-calcul avec filtrage. Cette thèse est consacrée à l'étude de systèmes de types pour ce calcul et à son utilisation dans le domaine de la déduction.Nous étudions deux paradigmes de typage. Le premier est inspiré du lambda-calcul simplement typé, mais un terme peut y être typé sans être terminant. Nous l'utilisons donc pour représenter des programmes et des systèmes de réécriture. La seconde famille de systèmes de types que nous étudions est adaptée des Pure Type Systems. Nous en démontrons la normalisation forte grâce à une traduction vers le lambda-calcul typé.Enfin nous proposons deux approches pour l'utilisation du calcul de réécriture en logique. La première consiste à définir des termes de preuve pour la déduction modulo à l'aide des systèmes fortement normalisants. Dans la seconde, nous définissons une généralisation de la déduction naturelle et nous montrons que le filtrage est utile pour représenter les règles de ce système de déduction

The simply-typed pure pattern type system ensures strong normalization

Abstract Pure Pattern Type Systems (P 2 T S) combine in a unified setting the capabilities of rewriting and λ-calculus. Their type systems, adapted from Barendregt’s λ-cube, are especially interesting from a logical point of view. Strong normalization, an essential property for logical soundness, had only been conjectured so far: in this paper, we give a positive answer for the simply-typed system. The proof is based on a translation of terms and types from P 2 T S into the λ-calculus. First, we deal with untyped terms, ensuring that reductions are faithfully mimicked in the λ-calculus. For this, we rely on an original encoding of the pattern matching capability of P 2 T S into the λ-calculus. Then we show how to translate types: the expressive power of System Fω is needed in order to fully reproduce the original typing judgments of P 2 T S. We prove that the encoding is correct with respect to reductions and typing, and we conclude with the strong normalization of simply-typed P 2 T S terms.

Typage et déduction dans le calcul de réécriture

Le calcul de réécriture est un lambda-calcul avec filtrage. Cette thèse est consacrée à l'étude de systèmes de types pour ce calcul et à son utilisation dans le domaine de la déduction. Nous étudions deux paradigmes de typage. Le premier est inspiré du lambda-calcul simplement typé, mais un terme peut y être typé sans être terminant. Nous l'utilisons donc pour représenter des programmes et des systèmes de réécriture. La seconde famille de systèmes de types que nous étudions est adaptée des Pure Type Systems. Nous en démontrons la normalisation forte grâce à une traduction vers le lambda-calcul typé. Enfin nous proposons deux approches pour l'utilisation du calcul de réécriture en logique. La première consiste à définir des termes de preuve pour la déduction modulo à l'aide des systèmes fortement normalisants. Dans la seconde, nous définissons une généralisation de la déduction naturelle et nous montrons que le filtrage est utile pour représenter les règles de ce système de déduction.The rewriting calculus is a lambda-calculus with pattern matching. This thesis is devoted to the study of type systems for this calculus, and to its use in the domain of deduction. We study two typing paradigms. The first one is inspired by the simply-typed lambda-calculus, but it differs from it in the sense that a term may be well-typed without being terminating. Thus, we use it for representing programs and rewriting systems. The second family of type systems we study is adapted from the Pure Type Systems. We show its strong normalization via a translation into a typed lambda-calculus. Finally, we propose two ways of using the rewriting calculus in logic. In the first approach, we use the strongly normalizing systems to define proof terms for deduction modulo. In the second, we define a generalization of natural deduction and we show that matching is useful in order to represent the rules of this deduction system.NANCY1-SCD Sciences & Techniques (545782101) / SudocNANCY-INRIA Lorraine LORIA (545472304) / SudocBORDEAUX1-Bib Rech. Maths-Info (335222209) / SudocSudocFranceF