3,624 research outputs found
Conformance relations for distributed testing based on CSP
Copyright @ 2011 Springer Berlin HeidelbergCSP is a well established process algebra that provides comprehensive theoretical and practical support for refinement-based design and verification of systems. Recently, a testing theory for CSP has also been presented. In this paper, we explore the problem of testing from a CSP specification when observations are made by a set of distributed testers. We build on previous work on input-output transition systems, but the use of CSP leads to significant differences, since some of its conformance (refinement) relations consider failures as well as traces. In addition, we allow events to be observed by more than one tester. We show how the CSP notions of refinement can be adapted to distributed testing. We consider two contexts: when the testers are entirely independent and when they can cooperate. Finally, we give some preliminary results on test-case generation and the use of coordination messages. Ā© 2011 IFIP International Federation for Information Processing
Sequential Composition in the Presence of Intermediate Termination (Extended Abstract)
The standard operational semantics of the sequential composition operator
gives rise to unbounded branching and forgetfulness when transparent process
expressions are put in sequence. Due to transparency, the correspondence
between context-free and pushdown processes fails modulo bisimilarity, and it
is not clear how to specify an always terminating half counter. We propose a
revised operational semantics for the sequential composition operator in the
context of intermediate termination. With the revised operational semantics, we
eliminate transparency, allowing us to establish a close correspondence between
context-free processes and pushdown processes. Moreover, we prove the reactive
Turing powerfulness of TCP with iteration and nesting with the revised
operational semantics for sequential composition.Comment: In Proceedings EXPRESS/SOS 2017, arXiv:1709.00049. arXiv admin note:
substantial text overlap with arXiv:1706.0840
On CSP and the Algebraic Theory of Effects
We consider CSP from the point of view of the algebraic theory of effects,
which classifies operations as effect constructors or effect deconstructors; it
also provides a link with functional programming, being a refinement of Moggi's
seminal monadic point of view. There is a natural algebraic theory of the
constructors whose free algebra functor is Moggi's monad; we illustrate this by
characterising free and initial algebras in terms of two versions of the stable
failures model of CSP, one more general than the other. Deconstructors are
dealt with as homomorphisms to (possibly non-free) algebras.
One can view CSP's action and choice operators as constructors and the rest,
such as concealment and concurrency, as deconstructors. Carrying this programme
out results in taking deterministic external choice as constructor rather than
general external choice. However, binary deconstructors, such as the CSP
concurrency operator, provide unresolved difficulties. We conclude by
presenting a combination of CSP with Moggi's computational {\lambda}-calculus,
in which the operators, including concurrency, are polymorphic. While the paper
mainly concerns CSP, it ought to be possible to carry over similar ideas to
other process calculi
A Design Strategy for Deadlock-Free Concurrent Systems
When building concurrent systems, it would be useful to have a collection of reusable processes
to perform standard tasks. However, without knowing certain details of the inner workings of
these components, one can never be sure that they will not cause deadlock when connected to
some particular network.
Here we describe a hierarchical method for designing complex networks of communicating
processeswhich are deadlock-free.We use this to define a safe and simple method for specifying
the communication interface to third party software components. This work is presented using
the CSP model of concurrency and the occam2.1 programming language
An algebra of discrete event processes
This report deals with an algebraic framework for modeling and control of discrete event processes. The report consists of two parts. The first part is introductory, and consists of a tutorial survey of the theory of concurrency in the spirit of Hoare's CSP, and an examination of the suitability of such an algebraic framework for dealing with various aspects of discrete event control. To this end a new concurrency operator is introduced and it is shown how the resulting framework can be applied. It is further shown that a suitable theory that deals with the new concurrency operator must be developed. In the second part of the report the formal algebra of discrete event control is developed. At the present time the second part of the report is still an incomplete and occasionally tentative working paper
Computation Tree Logic with Deadlock Detection
We study the equivalence relation on states of labelled transition systems of
satisfying the same formulas in Computation Tree Logic without the next state
modality (CTL-X). This relation is obtained by De Nicola & Vaandrager by
translating labelled transition systems to Kripke structures, while lifting the
totality restriction on the latter. They characterised it as divergence
sensitive branching bisimulation equivalence.
We find that this equivalence fails to be a congruence for interleaving
parallel composition. The reason is that the proposed application of CTL-X to
non-total Kripke structures lacks the expressiveness to cope with deadlock
properties that are important in the context of parallel composition. We
propose an extension of CTL-X, or an alternative treatment of non-totality,
that fills this hiatus. The equivalence induced by our extension is
characterised as branching bisimulation equivalence with explicit divergence,
which is, moreover, shown to be the coarsest congruence contained in divergence
sensitive branching bisimulation equivalence
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