Abstract. We study properties of asynchronous communication independently of any concrete concurrent process paradigm. We give a general-purpose, mathematically rigorous definition of several notions of asynchrony in a natural setting where an agent is asynchronous if its input and/or output is filtered through a buffer or a queue, possibly with feedback. In a series of theorems, we give necessary and sufficient conditions for each of these notions in the form of simple first-order or second-order axioms. We illustrate the formalism by applying it to asynchronous CCS and the core join calculus.

. This paper is included in a series aiming to contribute to the algebraic theory of distributed computation. The key problem in understanding Multi-Agent Systems is to find a theory which integrates the reactive part and the control part of such systems. To this end we use the calculus of flownomials. It is a polynomial-like calculus for representing flowgraphs and their behaviours. An `additive' interpretation of the calculus was intensively developed to study control flowcharts and finite automata. For instance, regular algebra and iteration theories are included in a unified presentation. On the other hand, a `multiplicative' interpretation of the calculus of flownomials was developed to study dataflow networks. The claim of this series of papers is that the mixture of the additive and multiplicative network algebras will contribute to the understanding of distributed computation. The role of this first paper is to present a few motivating examples. To appear in Journal of IGPL....

. This paper is included in a series aiming to contribute to the algebraic theory of distributed computation. The key problem in understanding Multi-Agent Systems is to find a theory which integrates the reactive part and the control part of such systems. The claim of this series of papers is that the mixture of the additive and multiplicative network algebras (MixNA) will contribute to the understanding of distributed computation. The aim of this part of the series is to make a short introduction to the kernel language FEST (Flownomial Expressions and System Tasks) based on MixNA. 1 Introduction FEST (Flownomial Expressions and System Tasks) is a kernel language under construction at UniBuc. Its main feature is a full integration of reactive and control modules. It has a clear mathematical semantics based on MixNA. 2 Unstructured FEST programs The unstructured FEST programs freely combine control and reactive modules. The wording "unstructured" referees to the fact that the basic s...

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The paper presents a simple format for typed logics with states by adding a function for register update to standard typed lambda calculus. It is shown that universal validity of equality for this extended language is decidable (extending a well-known result of Friedman for typed lambda calculus) . This system is next extended to a full fledged typed dynamic logic, and it is illustrated how the resulting format allows for very simple and intuitive representations of dynamic semantics for natural language and denotational semantics for imperative programming. The proposal is compared with some alternative approaches to formulating typed versions of dynamic logics. Keywords: type theory, compositionality, denotational semantics, dynamic semantics 1 Introduction A slight extension to the format of typed lambda calculus is enough to model states (assignments of values to storage cells) in a very natural way. Let a set R of registers or storage cells be given. If we assume that the values...

We use Tarski's relational calculus to construct a model of linear temporal logic. Both discrete and dense time are covered and we obtain denotational domains for a large variety of reactive systems. Keywords : Relational algebra, reactive systems, temporal algebra, temporal logic. 1