23,416 research outputs found
Semantic Embedding of Petri Nets into Event-B
We present an embedding of Petri nets into B abstract systems. The embedding
is achieved by translating both the static structure (modelling aspect) and the
evolution semantics of Petri nets. The static structure of a Petri-net is
captured within a B abstract system through a graph structure. This abstract
system is then included in another abstract system which captures the evolution
semantics of Petri-nets. The evolution semantics results in some B events
depending on the chosen policies: basic nets or high level Petri nets. The
current embedding enables one to use conjointly Petri nets and Event-B in the
same system development, but at different steps and for various analysis.Comment: 16 pages, 3 figure
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An algebra of high level petri nets
PhD ThesisPetri nets were introduced by C.A. Petri as a theoretical model of concurrency in which the causal
relationship between actions, rather than just their temporal ordering, can be represented. As
a theoretical model of concurrency, Petri nets have been widely successful. Moreover, Petri nets
are popular with practitioners, providing practical tools for the designer and developer of real
concurrent and distributed systems.
However, it is from this second context that perhaps the most widely voiced criticism of Petri
nets comes. It is that Petri nets lack any algebraic structure or modularity, and this results in
large, unstructured models of real systems, which are consequently often intractable. Although
this is not a criticism of Petri nets per se, but rather of the uses to which Petri nets are put, the
criticism is well taken.
We attempt to answer this criticism in this work. To do this we return to the view of Petri nets
as a model of concurrency and consider how other models of concurrency counter this objection.
The foremost examples are then the synchronisation trees of Milner, and the traces of Hoare,
(against which such criticism is rarely, if ever, levelled). The difference between the models is
clear, and is to be found in the richness of the algebraic characterisations which have been made
for synchronisation trees in Milner's Calculus of Communicating Systems (CCS), and for traces
in Hoare's Communicating Sequential Processes (CSP).
With this in mind we define, in this thesis, a class of high level Petri nets, High Level Petri Boxes,
and provide for them a very general algebraic description language, the High Level Petri Box
Algebra, with novel ideas for synchronisation, and including both refinement and recursion among
its operators. We also begin on the (probably open-ended task of the) algebraic characterisation
of High Level Petri Boxes.
The major contribution of this thesis is a full behavioural characterisation of the High Level Petri
Boxes which form the semantic domain of the algebra. Other contributions are: a very general
method of describing communication protocols which extend the synchronisation algebras of
Winskel; a recursive operator that preserves finiteness of state (the best possible, given the
generality of the algebra); a refinement operator that is syntactic in nature, and for which the
recursive construct is a behavioural fix-point; and a notion of behavioural equivalence which is
a congruence with respect to a major part of the High Level Petri Box Algebra
Z and high level Petri nets
High level Petri nets have tokens with values, traditionally called colors, and transitions that produce tokens in a functional way, using the consumed tokens as arguments of the function application. Large nets should be designed in a topdown approach and therefore we introduce a hierarchical net model which combines a data flow diagram technique with a high level Petri net model. We use Z to specify this net model, which is in fact the metamodel for specific systems. Specific models we specify partly by diagrams and partly in Z. We give some advantages and disadvantages of using Z in this way. Finally we show how to specify systems by means of an example
Augmenting High-Level Petri Nets to Support GALS Distributed Embedded Systems Specification
Part 9: Embedded Systems and Petri NetsInternational audienceHigh-level Petri net classes are suited to specify concurrent processes with emphasis both in control and data processing, making them appropriate to specify distributed embedded systems (DES). Embedded systems components are usually synchronous, which means that DES can be seen as Globally-Asynchronous Locally-Synchronous (GALS) systems. This paper proposes to include in high-level Petri nets a set of concepts already introduced for low-level Petri nets allowing the specification of GALS systems, namely time domains, test arcs and priorities. Additionally, this paper proposes external messages and three types of (high-level) asynchronous communication channels, to specify the interaction between distributed components based on message exchange. With these extensions, GALS-DES can be specified using high-level Petri nets. The resulting models include the specification of each component with well-defined boundaries and interface, and also the explicit specification of the asynchronous interaction between components. These models will be used not only to specify the system behavior, but also to be the input for model-checking tools (supporting its verification) and automatic code generation tools (supporting its implementation in software and hardware platforms), giving a contribution to the model-based development approach and hardware-software co-design of DES based on high-level Petri nets
Practical Use of High-level Petri Nets
This booklet contains the proceedings of the Workshop on Practical Use of High-level Petri Nets, June 27, 2000. The workshop is part of the 21st International Conference on Application and Theory of Petri Nets organised by the CPN group at the Department of Computer Science, University of Aarhus, Denmark. The workshop papers are available in electronic form via the web pages: http://www.daimi.au.dk/pn2000/proceeding
Practical Use of High-level Petri Nets
This booklet contains the proceedings of the Workshop on Practical Use of High-level Petri Nets, June 27, 2000. The workshop is part of the 21st International Conference on Application and Theory of Petri Nets organised by the CPN group at the Department of Computer Science, University of Aarhus, Denmark. The workshop papers are available in electronic form via the web pages: http://www.daimi.au.dk/pn2000/proceeding
MathMC: A mathematica-based tool for CSL model checking of deterministic and stochastic Petri nets
Deterministic and Stochastic Petri Nets (DSPNs) are a widely used high-level formalism for modeling discreteevent systems where events may occur either without consuming time, after a deterministic time, or after an exponentially distributed time. CSL (Continuous Stochastic Logic) is a (branching) temporal logic developed to express probabilistic properties in continuous time Markov chains (CTMCs). In this paper we present a Mathematica-based tool that implements recent developments for model checking CSL style properties on DSPNs. Furthermore, as a consequence of the type of process underlying DSPNs (a superset of Markovian processes), we are also able to check CSL properties of Generalized Stochastic Petri Nets (GSPNs) and labeled CTMCs
Supervisory Control and High-level Petri nets
The Supervisory Control Theory (SCT) (Ramadge & Wonham, 1989) was developed to provide a formal methodology for the automatic synthesis of controllers for Discrete Event Systems (DES). In this theory, a system, called a plant, is assumed to have uncontrollable behaviours which may violate some desired specifications. Hence, these behaviours have to be controlle
Structuring and composability issues in Petri nets modeling
Along Petri nets' history, numerous approaches have been proposed that try to manage model size through the introduction of structuring mechanisms allowing hierarchical representations and model composability. This paper proposes a classification system for Petri nets' structuring mechanisms and discusses each one of them. These include node fusion, node vectors, high-level nets, and object-oriented inspired Petri nets extensions, among others. One running example is used emphasizing the application of the presented mechanisms to specific areas, namely to automation systems modeling, and software engineering, where object-oriented modeling plays a major role
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