on the continuity of the map ϑ ϑ from the predual of a w algebra abstract let be elements in the predual of a w algebra for their absolute value parts the estimate 2 1 2 is obtained

complex classical fields a framework for reflection positivity we explore a framework for complex classical fields appropriate for describing quantum field theories our fields are linear transformations on a hilbert space so they are more general than random variables for a probability measure our method generalizes osterwalder and schrader s construction of euclidean fields we allow complex valued classical fields in the case of quantum field theories that describe neutral particles

full abstraction for pcf an intensional model for the programming language pcf is described in which the types of pcf are interpreted by games and the terms by certain history free strategies this model is shown to capture definability in pcf more precisely every compact strategy in the model is definable in a certain simple extension of pcf we then introduce an intrinsic preorder on strategies and show that it satisfies some striking properties such that the intrinsic preorder on function types coincides with the pointwise preorder we then obtain an order extensional fully abstract model of pcf by quotienting the intensional model by the intrinsic preorder this is the first syntax independent description of the fully abstract model for pcf hyland and ong have obtained very similar results by a somewhat different route independently and at the same time we then consider the effective version of our model and prove a universality theorem every element of the effective extensional model is definable in pcf equivalently every recursive strategy is definable up to observational equivalence

on the p calculus and linear logic abstract we detail abramsky s proofs as processes paradigm for interpreting classical linear logic cll girard 1987 into a synchronous version of the calculus recently proposed by milner 1992 1993 the translation is given at the abstract level of proof structures we give a detailed treatment of information flow in proof nets and show how to mirror various evaluation strategies for proof normalization we also give soundness and completeness results for the process calculus translations of various fragments of cll the paper also gives a self contained introduction to some of the deeper proof theory of cll and its process interpretation

syntax vs semantics a polarized approach we present a notion of sliced proof nets for the polarized fragment of linear logic and a corresponding game model we show that the connection between them is very strong through an equivalence of categories this contains soundness full completeness and faithful completeness

the obnoxious p facility network location problem with facility interaction three heuristics are proposed to solve the maximin formulation for siting p facilities on a network considering a pollution dispersion equation and facility interaction initially the single facility problem is approached by building up polygons which model pollution spread about the nodes of the network this is extended in the first heuristic to the p facility problem the second combines both the p maximin and p maxisum objectives in a lexicographic manner the third is based on recent developments of simulated annealing the proposed heuristics are evaluated for up to six facilities on a set of randomly generated networks having 20 to 40 nodes and low or medium arc density

an analysis of network location problems with distance constraints this paper concerns a class of network location problems with minimum or maximum separation requirements between uncapacitated facilities or between demand points and the facilities or both its purpose is three fold first it is to recognize distance constraints as increasing real life restrictions through various motivating illustrations using a new classification scheme the paper introduces a variety of distance constrained problems defined in a unified manner these include a number of new problems second it is to survey existing solution techniques available only for a few of such constrained problems finally it is to shed some light on yet unstudied problems by exploring possible extensions of some of the known solution techniques or discussing varying degrees of difficulties involved in particular the paper presents integer programming formulations of several new problems along with the results of applying linear programming relaxation methods although the computational experience is somewhat disappointing for some of these problems the results provide greater insight into the problems with the stated purpose it is hoped that this paper will stimulate future research in this important problem area

green s function for a hierarchical self avoiding walk in four dimensions this is the second of two papers on the end to end distance of a weakly self repelling walk on a four dimensional hierarchical lattice it completes the proof that the expected value grows as a constant times sqrt t log frac 1 8 t left 1 o left frac log log t log t right right which is the same law as has been conjectured for self avoiding walks on the simple cubic lattice 4 apart from completing the program in the first paper the main result is that the green s function is almost equal to the green s function for the markov process with no self repulsion but at a different value of the killing rate which can be accurately calculated when the interaction is small furthermore the green s function is analytic in in a sector in the complex plane with opening angle greater than

polarized proof nets and λµ calculus we first define polarized proof nets an extension of mell proof nets for the polarized fragment of linear logic the main difference with usual proof nets is that we allow structural rules on any negative formula the essential properties confluence strong normalization in the typed case of polarized proof nets are proved using a reduction preserving translation into usual proof nets we then give a reduction preserving encoding of parigot s terms for classical logic as polarized proof nets it is based on the intuitionistic translation a b a b so that it is a straightforward extension of the usual translation of calculus into proof nets we give a reverse encoding which sequentializes any polarized proof net as a term in the last part of the paper we extend the equivalence for calculus to calculus interestingly this new equivalence relation identifies normal terms we eventually show that two terms are equivalent iff they are translated as the same polarized proof net thus the set of polarized proof nets represents the quotient of calculus by equivalence

equivalence of euclidean and wightman field theories a new inversion formula for the laplace transformation of tempered distributions with supports in the closed positive semiaxis is obtained the inverse laplace transform of a tempered distribution is defined by means of a limit of a special distribution constructed from this distribution the weak spectral condition on the euclidean green s functions implies that some of the limits needed for the inversion formula exist for any euclidean green s function with an even number of variables we then prove that the initial osterwalder schrader axioms 1 and the weak spectral condition are equivalent with the wightman axioms

locating an undesirable facility with a minimax criterion abstract the problem considered in this paper involves the location of an undesirable facility such that the maximum weighted inverse square distance from the facility to n given points is minimized the region in which the facility is to be located is bounded and contains the n points with which the facility to be located will interact applications can include siting an undesirable facility that produces some form of pollutant such as radiation noise and some gases any problem that involves the location of a facility that emits pollutants whose concentrations follow the inverse square law is a candidate for the use of this work a mathematical programming algorithm is developed for the situation in which the location problem involves a convex polygonal region an interactive computer graphics approach is described for the case when the location problem involves a general region

typed event structures and the linear π calculus we propose a typing system for the true concurrent model of event structures that guarantees the interesting behavioural properties known as conflict freeness and confusion freeness conflict freeness is the true concurrent version of the notion of confluence a system is confusion free if nondeterministic choices are localised and do not depend on the scheduling of independent components ours is the first typing system to control behaviour in a true concurrent model to demonstrate its applicability we show that typed event structures give a semantics of linearly typed version of the p calculi with internal mobility the semantics we provide is the first event structure semantics of the p calculus and generalises winskel s original event structure semantics of ccs

causal independence and the energy level density of states in local quantum field theory within the general framework of local quantum field theory a physically motivated condition on the energy level density of well localized states is proposed and discussed it is shown that any model satisfying this condition obeys a strong form of the principle of causal statistical independence which manifests itself in a specific algebraic structure of the local algebras split property it is also shown that the proposed condition holds in a free field theory

advanced greedy randomized adaptive search procedure for the obnoxious p median problem abstract the obnoxious p median problem consists in selecting a subset of p facilities from a given set of possible locations in such a way that the sum of the distances between each customer and its nearest facility is maximized the problem is np hard and can be formulated as an integer linear program it was introduced in the 1990s and a branch and cut method coupled with a tabu search has been recently proposed in this paper we propose a heuristic method based on the greedy randomized adaptive search procedure grasp methodology for finding approximate solutions to this optimization problem in particular we consider an advanced grasp design in which a filtering mechanism avoids applying the local search method to low quality constructed solutions empirical results indicate that the proposed implementation compares favorably to previous methods this fact is confirmed with non parametric statistical tests

an equivalence between lambda terms resume dans ce papier on definit une relation d equivalence sur les lambda termes identifiant les termes qui ne different que par des permutations de radicaux la equivalence on demontre qu aucun des criteres operationnels standards de classification du lambda calcul e g la longueur de la plus longue normalisation ne permet de distinguer deux termes equivalents enfin la equivalence est utilisee pour demontrer une generalisation du theoreme de la strategie perpetuelle

behavioral equivalence in the polymorphic pi calculus we investigate parametric polymorphism in message based concurrent programming focusing on behavioral equivalences in a typed process calculus analogous to the polymorphic lambda calculus of girard and reynolds polymorphism constrains the power of observers by preventing them from directly manipulating data values whose types are abstract leading to notions of equivalence much coarser than the standard untyped ones we study the nature of these constraints through simple examples of concurrent abstract data types and develop basic theoretical machinery for establishing bisimilarity of polymorphic processes we also observe some surprising interactions between polymorphism and aliasing drawing examples from both the polymorphic pi calculus and ml

interpolation by type i factors and the flip automorphism abstract given two von neumann algebras a b we study the relation between the existence of an interpolating type i factor f namely a f b the implementability of the flip automorphism of a a by a unitary in b b and the statistical independence of a and b a and b generate a w tensor product as an application in q f t we derive in a natural way a structure theorem of buchholz for the von neumann algebras of local observables associated to free fields

euclidean invariant integral representations for schwinger functionals it is shown that if the schwinger functions of a wightman theory with a mass gap can be represented as moments of a complex measure there is also such a representation by a measure that is invariant under the euclidean group a necessary and sufficient condition is also given for the exponential of a quadratic form on the test function space to be the characteristic functional of a complex measure

local aspects of superselection rules we study a theory of short range forces in terms of local observable quantities among the superselection structure determined by the algebra of all local observables to each additive independent charge we associate local observables having a meaning analogous to the regularized integrals of charge density fields over a finite volume among other assumptions we require that parastatistics are absent from the theories considered

normal product states for fermions and twisted duality for ccr and car type algebras with application to the yukawa2 quantum field model we present sufficient conditions that imply duality for the algebras of local observables in all abelian sectors of all locally normal irreducible representations of a field algebra if twisted duality obtains in one of these representations it is verified that the yukawa2 model satisfies these conditions yielding the first proof of duality for the observable algebra in all coherent charge sectors in this model this paper also constitutes the first verification of the assumptions of the axiomatic study of the structure of superselection sectors by doplicher haag and roberts in an interacting model with nontrivial sectors the existence of normal product states for the free fermi field algebra and thus the verification of the funnel property for the associated net of local algebras are demonstrated

reflection positive doubles here we introduce reflection positive doubles a general framework for reflection positivity covering a wide variety of systems in statistical physics and quantum field theory these systems may be bosonic fermionic or parafermionic in nature within the framework of reflection positive doubles we give necessary and sufficient conditions for reflection positivity we use a reflection invariant cone to implement our construction our characterization allows for a direct interpretation in terms of coupling constants making it easy to check in concrete situations we illustrate our methods with numerous examples

some experiments with simulated annealing techniques for packing problems abstract experiments with a variety of combinatorial optimisation problems have shown that the simulated annealing algorithm is an effective local search heuristic method the basic requirements of the algorithm are a neighbourhood structure on the set of feasible solutions and a number of parameters which govern the acceptance or rejection of new solutions generated during the search the quality of the solution is very sensitive to both these factors this paper is concerned with the application of the simulated annealing approach to packing problems and describes a series of experiments carried out to ascertain the effectiveness of the method for such problems and the most appropriate neighbourhood structure to use and the best parameters to apply

concurrent nets a study of prefixing in process calculi we introduce the calculus of concurrent nets as an extension of the fusion calculus in which usual prefixing is replaced by arbitrary monotonic guards then we use this formalism to describe the prefixing policy of standard calculi as a particular form of communication by developing a graphical syntax we sharpen the geometric intuition and finally we provide an encoding of these guards as causality in the prefix free fragment in the spirit of the encoding of the fusion calculus into solos by laneve and victor proving that communication by fusion is expressive enough to implement arbitrary monotonic guards

interpreting a finitary pi calculus in differential interaction nets we propose and study a translation of a pi calculus without sums nor recursion into an untyped version of differential interaction nets we define a transition system of labeled processes and a transition system of labeled differential interaction nets we prove that our translation from processes to nets is a bisimulation between these two transition systems this shows that differential interaction nets are sufficiently expressive for representing concurrency and mobility as formalized by the pi calculus our study will concern essentially a replication free fragment of the pi calculus but we shall also give indications on how to deal with a restricted form of replication

complex classical fields an example abstract we study complex classical scalar fields within a new framework introduced in a previous work we replace the usual functional integral by a complex functional arising from a boosted hamiltonian we generalize the feynman kac relation to this setting and use it to establish the spectral condition on a cylinder we consider also positive temperature states

an exact correspondence between a typed pi calculus and polarised proof nets this paper presents an exact correspondence in typing and dynamics between polarised linear logic and a typed p calculus based on io typing the respective incremental constraints one on geometric structures of proof nets and one based on types precisely correspond to each other leading to the exact correspondence of the respective formalisms as they appear in olivier laurent 2003 27 for proof nets and kohei honda et al 2004 24 for the p calculus

computational interpretations of linear logic abstract we study girard s linear logic from the point of view of giving a concrete computational interpretation of the logic based on the curry howard isomorphism in the case of intuitionistic linear logic this leads to a refinement of the lambda calculus giving finer control over order of evaluation and storage allocation while maintaining the logical content of programs as proofs and computation as cut elimination in the classical case it leads to a concurrent process paradigm with an operational semantics in the style of berry and boudol s chemical abstract machine this opens up a promising new approach to the parallel implementation of functional programming languages and offers the prospect of typed concurrent programming in which correctness is guaranteed by the typing

strong normalisation in the π calculus we introduce a typed calculus where strong normalisation is ensured by typability strong normalisation is a useful property in many computational contexts including distributed systems in spite of its simplicity our type discipline captures a wide class of converging name passing interactive behaviour the proof of strong normalisability combines methods from typed calculi and linear logic with process theoretic reasoning it is adaptable to systems involving state non determinism polymorphism control and other extensions strong normalisation is shown to have significant consequences including finite axiomatisation of weak bisimilarity a fully abstract embedding of the simply typed calculus with products and sums and basic liveness in interaction strong normalisability has been extensively studied as a fundamental property in functional calculi term rewriting and logical systems this work is one of the first steps to extend theories and proof methods for strong normalisability to the context of name passing processes