331 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
Fair Pi
International audienceIn this paper, we define fair computations in the pi-calculus. We follow Costa and Stirling's approach for CCS-like languages but exploit a more natural labeling method of process actions to filter out unfair process executions. The new labeling allows us to prove all the significant properties of the original one, such as unicity, persistence and disappearance of labels. It also turns out that the labeled pi-calculus is a conservative extension of the standard one. We contrast the existing fair testing with those that naturally arise by imposing weak and strong fairness as defined by Costa and Stirling. This comparison provides the expressiveness of the various fair testing-based semantics and emphasizes the discriminating power of the one already proposed in the literature
Fair Î
AbstractIn this paper, we define fair computations in the π-calculus [Milner, R., Parrow, J. & Walker, D., A Calculus of Mobile Processes, Part I and II, Information and Computation 100 (1992) 1–78]. We follow Costa and Stirling's approach for CCS-like languages [Costa, G. & Stirling, C., A Fair Calculus of Communicating Systems, Acta Informatica 21 (1984) 417–441, Costa, G. & Stirling, C., Weak and Strong Fairness in CCS, Information and Computation 73 (1987) 207–244] but exploit a more natural labeling method of process actions to filter out unfair process executions. The new labeling allows us to prove all the significant properties of the original one, such as unicity, persistence and disappearance of labels. It also turns out that the labeled π-calculus is a conservative extension of the standard one. We contrast the existing fair testing [Brinksma, E., Rensink, A. & Vogler, W., Fair Testing, Proc. of CONCUR'95, LNCS, 962 (1995) 313–327, Natarajan, V. & Cleaveland, R., Divergence and Fair Testing, Proc. of ICALP '95, LNCS, 944 (1995) 648–659] with those that naturally arise by imposing weak and strong fairness as defined by Costa and Stirling. This comparison provides the expressiveness of the various fair testing-based semantics and emphasizes the discriminating power of the one already proposed in the literature
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
An Individual-based Probabilistic Model for Fish Stock Simulation
We define an individual-based probabilistic model of a sole (Solea solea)
behaviour. The individual model is given in terms of an Extended Probabilistic
Discrete Timed Automaton (EPDTA), a new formalism that is introduced in the
paper and that is shown to be interpretable as a Markov decision process. A
given EPDTA model can be probabilistically model-checked by giving a suitable
translation into syntax accepted by existing model-checkers. In order to
simulate the dynamics of a given population of soles in different environmental
scenarios, an agent-based simulation environment is defined in which each agent
implements the behaviour of the given EPDTA model. By varying the probabilities
and the characteristic functions embedded in the EPDTA model it is possible to
represent different scenarios and to tune the model itself by comparing the
results of the simulations with real data about the sole stock in the North
Adriatic sea, available from the recent project SoleMon. The simulator is
presented and made available for its adaptation to other species.Comment: In Proceedings AMCA-POP 2010, arXiv:1008.314
Building a MultiAgent System from a User Workflow Specification
This paper provides a methodology to build
a MultiAgent System (MAS) described in terms of interactive
components from a domain-specic User Workow
Specication (UWS). We use a Petri nets-based notation
to describe workow specications. This, besides using a
familiar and well-studied notation, guarantees an highlevel
of description and independence with more concrete
vendor-specic process denition languages. In order to
bridge the gap between workow specications and MASs,
we exploit other intermediate Petri nets-based notations.
Transformation rules are given to translate a notation to
another. The generated agent-based application implements
the original workow specication. Run-time support is
provided by a middleware suitable for the execution of the
generated code
Timed Process Calculi: From Durationless Actions to Durational Ones
Several timed process calculi have been proposed in the literature, which mainly differ for the way in which delays are represented. In particular, a distinction is made between integrated-time calculi, in which actions are durational, and orthogonal-time calculi, in which actions are instantaneous and delays are expressed separately. To reconcile the two approaches, in a previous work an encoding from the integrated-time calculus CIPA to the orthogonal-time calculus TCCS was defined, which preserves timed bisimilarity. To complete the picture, in this paper we consider the reverse translation, by examining the modifications to the two calculi that are needed to make an encoding feasible, as well as the behavioral equivalence that is appropriate to preserve. We then introduce an encoding from modified TCCS to modified CIPA, and show that it can only preserve the weak variant of timed bisimilarity
- …