David J. Pym

The Semantics and Proof Theory of the Logic of Bunched Implications

List of Figures. List of Tables. Preface. Acknowledgments. Foreword. Introduction David J. Pym. Part I: Propositional BI. 1. Introduction to Part I. 2. Natural Deduction for Propositional BI. 3. Algebraic, Topological, Categorical. 4. Kripke Semantics. 5. Topological Kripke Semantics. 6. Propositional BI as a Sequent Calculus. 7. Towards Classical Propositional BI. 8. Bunched Logical Relations. 9. The Sharing Interpretation, I. Part II: Predicate BI. 10. Introduction to Part II. 11. The Syntax of Predicate BI. 12. Natural Deduction & Sequent Calculus For Predicate BI. 13. Kripke Semantics for Predicate BI. 14. Topological Kripke Semantics for Predicate BI. 15. Resource Semantics, Type Theory & Fibred Categories. 16. The Sharing Interpretation, II. Bibliography. Index.

Possible worlds and resources: the semantics of BI

The logic of bunched implications, BI, is a substructural system which freely combines an additive (intuitionistic) and a multiplicative (linear) implication via bunches (contexts with two combining operations, one which admits Weakening and Contraction and one which does not). BI may be seen to arise from two main perspectives. On the one hand, from proof-theoretic or categorical concerns and, on the other, from a possible-worlds semantics based on preordered (commutative) monoids. This semantics may be motivated from a basic model of the notion of resource. We explain BIs proof-theoretic, categorical and semantic origins. We discuss in detail the question of completeness, explaining the essential distinction between BI with and without ⊥ (the unit of V). We give an extensive discussion of BI as a semantically based logic of resources, giving concrete models based on Petri nets, ambients, computer memory, logic programming, and money.

A Uniform Proof-theoretic Investigation of Linear Logic Programming

In this paper we consider the problem of identifying logic programming languages for linear logic. Our analysis builds on a notion of goal-directed provability, characterized by the so-called uniform proofs, previously introduced for minimal and intuitionistic logic. A class of uniform proofs in linear logic is identiied by an analysis of the permutability of inferences in the linear sequent calculus. We show that this class of proofs is complete (for logical consequence) for a certain (quite large) fragment of linear logic, which thus forms a logic programming language. We obtain a notion of resolution proof, in which only one left rule, of clause-directed resolution, is required. We also consider a translation, resembling those of Girard, of the hereditary Harrop fragment of intuitionistic logic into our framework. We show that goal-directed provability is preserved under this translation.

The semantics of BI and resource tableaux

The logic of bunched implications, BI, provides a logical analysis of a basic notion of resource that is rich enough, for example, to form the logical basis for ‘pointer logic’ and ‘separation logic’ semantics for programs that manipulate mutable data structures. We develop a theory of semantic tableaux for BI, so providing an elegant basis for efficient theorem proving tools for BI. It is based on the use of an algebra of labels for BIs tableaux to solve the resource-distribution problem, the labels being the elements of resource models. For BI with inconsistency,

Programming in Lygon: An Overview

\bot

A Calculus and logic of resources and processes

, the challenge consists in dealing with BIs Grothendieck topological models within such a proof-search method, based on labels. We prove soundness and completeness theorems for a resource tableaux method TBI with respect to this semantics and provide a way to build countermodels from so-called dependency graphs. Then, from these results, we can define a new resource semantics of BI, based on partially defined monoids, and prove that this semantics is complete. Such a semantics, based on partiality, is closely related to the semantics of BIs (intuitionistic) pointer and separation logics. Returning to the tableaux calculus, we propose a new version with liberalised rules for which the countermodels are closely related to the topological Kripke semantics of BI. As consequences of the relationships between semantics of BI and resource tableaux, we prove two new strong results for propositional BI: its decidability and the finite model property with respect to topological semantics.

Algebra and logic for resource-based systems modelling

For many given systems of logic, it is possible to identify, via systematic proof-theoretic analyses, a fragment which can be used as a basis for a logic programming language. Such analyses have been applied to linear logic, a logic of resource-consumption, leading to the definition of the linear logic programming language Lygon. It appears that (the basis of) Lygon can be considered to be the largest possible first-order linear logic programming language derivable in this way. In this paper, we describe the design and application of Lygon. We give examples which illustrate the advantages of resource-oriented logic programming languages.

On bunched predicate logic

Recent advances in logics for reasoning about resources provide a new approach to compositional reasoning in interacting systems. We present a calculus of resources and processes, based on a development of Milner’s synchronous calculus of communication systems, SCCS, that uses an explicit model of resource. Our calculus models the co-evolution of resources and processes with synchronization constrained by the availability of resources. We provide a logical characterization, analogous to Hennessy–Milner logic’s characterization of bisimulation in CCS, of bisimulation between resource processes which is compositional in the concurrent and local structure of systems.

Investments and Trade-offs in the Economics of Information Security

Mathematical modelling is one of the fundamental tools of science and engineering. Very often, models are required to be executable, as a simulation, on a computer. In this paper, we present some contributions to the process-theoretic and logical foundations of discrete-event modelling with resources and processes. We present a process calculus with an explicit representation of resources in which processes and resources co-evolve. The calculus is closely connected to a logic that may be used as a specification language for properties of models. The logic is strong enough to allow requirements that a system has a certain structure: for example, that it is a parallel composite of subsystems. This work consolidates, extends and improves upon aspects of earlier work of ours in this area. An extended example, consisting of a semantics for a simple parallel programming language, indicates a connection with separating logics for concurrency.

A Logical and Computational Theory of Located Resource

We present the logic of bunched implications, BI, in which a multiplicative (or linear) and an additive (or intuitionistic) implication live side-by-side. The propositional version of BI arises from an analysis of the proof-theoretic relationship between conjunction and implication, and may be viewed as a merging of intuitionistic logic and multiplicative, intuitionistic linear logic. The predicate version of BI includes, in addition to usual additive quantifiers, multiplicative (or intensional) quantifiers /spl forall//sub new/, and /spl exist//sub new/, which arise from observing restrictions on structural rules on the level of terms as well as propositions. Moreover, these restrictions naturally allow the distinction between additive predication and multiplicative predication for each propositional connective. We provide a natural deduction system, a sequent calculus, a Kripke semantics and a BHK semantics for BI. We mention computational interpretations, based on locality and sharing, at both the propositional and predicate levels. We explain BIs relationship with intuitionistic logic, linear logic and other relevant logics.