2,850 research outputs found
Read Operators and their Expressiveness in Process Algebras
We study two different ways to enhance PAFAS, a process algebra for modelling
asynchronous timed concurrent systems, with non-blocking reading actions. We
first add reading in the form of a read-action prefix operator. This operator
is very flexible, but its somewhat complex semantics requires two types of
transition relations. We also present a read-set prefix operator with a simpler
semantics, but with syntactic restrictions. We discuss the expressiveness of
read prefixes; in particular, we compare them to read-arcs in Petri nets and
justify the simple semantics of the second variant by showing that its
processes can be translated into processes of the first with timed-bisimilar
behaviour. It is still an open problem whether the first algebra is more
expressive than the second; we give a number of laws that are interesting in
their own right, and can help to find a backward translation.Comment: In Proceedings EXPRESS 2011, arXiv:1108.407
Generalized Communicating P Systems Working in Fair Sequential Model
In this article we consider a new derivation mode for generalized
communicating P systems (GCPS) corresponding to the functioning of population
protocols (PP) and based on the sequential derivation mode and a fairness
condition. We show that PP can be seen as a particular variant of GCPS. We also
consider a particular stochastic evolution satisfying the fairness condition
and obtain that it corresponds to the run of a Gillespie's SSA. This permits to
further describe the dynamics of GCPS by a system of ODEs when the population
size goes to the infinity.Comment: Presented at MeCBIC 201
Analysing Mutual Exclusion using Process Algebra with Signals
In contrast to common belief, the Calculus of Communicating Systems (CCS) and
similar process algebras lack the expressive power to accurately capture mutual
exclusion protocols without enriching the language with fairness assumptions.
Adding a fairness assumption to implement a mutual exclusion protocol seems
counter-intuitive. We employ a signalling operator, which can be combined with
CCS, or other process calculi, and show that this minimal extension is
expressive enough to model mutual exclusion: we confirm the correctness of
Peterson's mutual exclusion algorithm for two processes, as well as Lamport's
bakery algorithm, under reasonable assumptions on the underlying memory model.
The correctness of Peterson's algorithm for more than two processes requires
stronger, less realistic assumptions on the underlying memory model.Comment: In Proceedings EXPRESS/SOS 2017, arXiv:1709.0004
Explicit fairness in testing semantics
In this paper we investigate fair computations in the pi-calculus. Following
Costa and Stirling's approach for CCS-like languages, we consider a method to
label process actions in order to filter out unfair computations. We contrast
the existing fair-testing notion with those that naturally arise by imposing
weak and strong fairness. This comparison provides insight about the
expressiveness of the various `fair' testing semantics and about their
discriminating power.Comment: 27 pages, 1 figure, appeared in LMC
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