2,577 research outputs found
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
Modelling Mutual Exclusion in a Process Algebra with Time-outs
I show that in a standard process algebra extended with time-outs one can
correctly model mutual exclusion in such a way that starvation-freedom holds
without assuming fairness or justness, even when one makes the problem more
challenging by assuming memory accesses to be atomic. This can be achieved only
when dropping the requirement of speed independence.Comment: arXiv admin note: text overlap with arXiv:2008.1335
Modelling and analysing software in mCRL2
Model checking is an effective way to design correct software.Making behavioural models of software, formulating correctness properties using modal formulas, and verifying these using finite state analysis techniques, is a very efficient way to obtain the required insight in the software. We illustrate this on four common but tricky examples
Reactive Bisimulation Semantics for a Process Algebra with Time-Outs
This paper introduces the counterpart of strong bisimilarity for labelled transition systems extended with time-out transitions. It supports this concept through a modal characterisation, congruence results for a standard process algebra with recursion, and a complete axiomatisation
A process algebra with global variables
In standard process algebra, parallel components do not share a common state
and communicate through synchronisation. The advantage of this type of
communication is that it facilitates compositional reasoning. For modelling and
analysing systems in which parallel components operate on shared memory,
however, the communication-through-synchronisation paradigm is sometimes less
convenient. In this paper we study a process algebra with a notion of global
variable. We also propose an extension of Hennessy-Milner logic with predicates
to test and set the values of the global variables, and prove correspondence
results between validity of formulas in the extended logic and stateless
bisimilarity and between validity of formulas in the extended logic without the
set operator and state-based bisimilarity. We shall also present a translation
from the process algebra with global variables to a fragment of mCRL2 that
preserves the validity of formulas in the extended Hennessy-Milner logic.Comment: In Proceedings EXPRESS/SOS 2020, arXiv:2008.1241
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