Algebra of communicating processes with abstraction

Journal of the ACM, 1989

Lecture Notes in Computer Science, 1993

Lecture Notes in Computer Science, 1991

Lecture Notes in Computer Science, 2007

In this paper, we mainly focus on solving scheduling problems with model checking, where a finite number of entities needs to be processed as efficiently as possible, for instance by a machine. To solve these problems, we model them in untimed process algebra, where time is modelled using a special tick action. We propose a set of distributed state space explorations to find schedules for the modelled problems, building on the traditional notion of beam search. The basic approach is called distributed (detailed) beam search, which prunes parts of the state space while searching using an evaluation function in order to find near-optimal schedules in very large state spaces. Variations on this approach are presented, such as distributed flexible, distributed g-synchronised, and distributed priority beam search, which can also practically be used in combinations.

Theoretical Computer Science, 1987

Lecture Notes in Computer Science, 2010

In this paper, we propose the notion of partial time abstraction for timed process algebras, which introduces the possibility to abstract away parts of the timing of system behaviour. Adding this notion leads to so-called partially timed process algebras and partially timed labelled transition systems. We describe these notions, and generalise timed branching bisimilarity to partially timed branching bisimilarity, allowing the comparison of systems with partial timing. Finally, with several examples and a case study, we demonstrate how partial time abstraction can be a useful modelling technique for timed models, which can lead to rigorous minimisations of state spaces.

Lecture Notes in Computer Science, 1996

Recently there has been a spurt of activity in concurrency theory centred on the analysis of in nite-state systems. Much of this work stems from a task dedicated to the study in the recently-concluded ESPRIT BRA Concur2, and much of it has subsequently appeared in the proceedings of the annual CONCUR conference. In this paper, we present an overview of various results obtained regarding expressivity, decidability, and complexity, focussing on the various techniques exploited in each case.

Lecture Notes in Computer Science, 2012

Lecture Notes in Computer Science, 2010

We provide an equational theory for Restricted Broadcast Process Theory to reason about ad hoc networks. We exploit an extended algebra called Computed Network Theory to axiomatize restricted broadcast. It allows one to define the behavior of an ad hoc network with respect to the underlying topologies. We give a sound and ground-complete axiomatization for CNT terms with finite-state behavior, modulo what we call rooted branching computed network bisimilarity.

Lecture Notes in Computer Science, 1991

ACM Transactions on Software Engineering and Methodology, 2014

Sequence diagrams are a widely used design notation for describing software behaviors. Many reusable software artifacts such as design patterns and design aspects make use of sequence diagrams to describe interaction behaviors. When a pattern or an aspect is reused in an application, it is important to ensure that the sequence diagrams for the application conform to the corresponding sequence diagrams for the pattern or aspect. Reasoning about conformance relationship between sequence diagrams has not been addressed adequately in literature. In this paper, we focus on required behavior specified by a UML sequence diagram. A novel trace semantics is given that captures precisely required behavior specified by a sequence diagram and a conformance relation between sequence diagrams is formalized based on the semantics. Properties of the trace semantics and the conformance relation are studied.

SIAM Journal on Computing, 1988

Lecture Notes in Computer Science

We verify a simple verslon o? the alternating bit protocol in the system ACP~ (Algebra of Communicating Processes with silent actions) augmented with Koomenls falr abstraction rule.

Linear Time, Branching Time and Partial Order in Logics and Models for Concurrency

In this paper a process is viewed as a labeled graph modulo bisimulation equivalence. Three topics are covered: (i) specification of processes using finite systems of equations over the syntax of process algebra; (ii) inference systems which are complete for proving the equivalence of regular (finite state) processes; (iii) variations of the bisimulation model.

Formal Aspects of Computing, 1993

TIC is a timed algebraic calculus which combines ideas from asynchronous and synchronous calculi Time is introduced by assigning explicit time restrictions to the events of an asynchronous calculus The semantics is defined in an operational way. Interleaving of behaviours is defined-in.such a way that a ptop"i metg" of events in time is achieved. Weak timed bisimulation is also dehned. Examples are presented to show the applicability of the calculus to the study of timed behaviours. * This work was partially supporled by CICYT u¡der the TIC program (MEDAS p¡oject) Correspondence nia o¡print ,"qu"rt, to, Juan Quemada.

Lecture Notes in Computer Science, 2014

Session types are types for distributed communicating processes. They were born from process encodings of data structures and typical interaction scenarios in an asynchronous version of the π-calculus, and are being studied and developed as a potential basis for structuring concurrent and distributed computing, as well as in their own right. In this paper, we introduce basic ideas of sessions and session types, outline their key technical elements, and discuss how they may be usable for programming, drawing from our experience and comparing with existing paradigms, especially concurrent objects such as actors. We discuss how session types can offer a programming framework in which communications are structured both in program text and at run-time.

Journal of Computer and System Sciences, 1987

The main problem in recursive scheme theory is determining how to solve a scheme and express its solution. Up to now this was always achieved by adding restrictive hypotheses either on the schemes themselves, or on the domains where they take their values, e.g., assuming the domains have a metric or an order structure and are complete with respect to this structure, or are iterative. Here we develop a strictly algebraic theory of recursion schemes with second-order substitutions. As it is strictly algebraic, the theory applies not only to all recursion schemes on trees, but also to recursion schemes on arbitrary algebras presented in the usual way by generators and relations. In particular, this gives a semantics for nondeterminism and for process algebras.

International Journal of Computer Mathematics, 1997

Network algebra is proposed as a uniform algebraic framework for the description and analysis of dataflow networks. An equational theory of networks, called BNA (Basic Network Algebra), is presented. BNA, which is essentially a part of the algebra of flownomials, captures the basic algebraic properties of networks. For asynchronous dataflow networks, additional constants and axioms are given; and a corresponding process algebra model is introduced. This process algebra model is compared with previous models for asynchronous dataflow.

Constraints, 2013

Concurrent Constraint Programming (CCP) has been used over the last two decades as an elegant and expressive model for concurrent systems. It models systems of agents communicating by posting and querying partial information, represented as constraints over the variables of the system. This covers a vast variety of systems as those arising in biological phenomena, reactive systems, netcentric computing and the advent of social networks and cloud computing. In this paper we survey the main applications, developments and current trends of CCP.

STACS 99, 1999

We study a logic called FLC (Fixpoint Logic with Chop) that extends the modal mu-calculus by a chop-operator and termination formulae. For this purpose formulae are interpreted by predicate transformers instead of predicates. We show that any context-free process can be characterized by an FLC-formula up to bisimulation or simulation. Moreover, we establish the following results: FLC is strictly more expressive than the modal mu-calculus; it is decidable for finite-state processes but undecidable for context-free processes; satisfiability and validity are undecidable; FLC does not have the finite-model property.