750 research outputs found
Membrane Systems and Petri Net Synthesis
Automated synthesis from behavioural specifications is an attractive and
powerful way of constructing concurrent systems. Here we focus on the problem
of synthesising a membrane system from a behavioural specification given in the
form of a transition system which specifies the desired state space of the
system to be constructed. We demonstrate how a Petri net solution to this
problem, based on the notion of region of a transition system, yields a method
of automated synthesis of membrane systems from state spaces.Comment: In Proceedings MeCBIC 2012, arXiv:1211.347
Integration of an object formalism within a hybrid dynamic simulation environment
PrODHyS is a general object-oriented environment which provides common and reusable components designed for the development and the management of dynamic simulation of systems engineering. Its major characteristic is its ability to simulate processes described by a hybrid model. In this framework, this paper focuses on the "Object Differential Petri Net" (ODPN) formalism integrated within PrODHyS. The use of this formalism is illustrated through a didactic example relating to the field of Chemical Process System Engineering (PSE)
Reconfigurable Decorated PT Nets with Inhibitor Arcs and Transition Priorities
In this paper we deal with additional control structures for decorated PT
Nets. The main contribution are inhibitor arcs and priorities. The first ensure
that a marking can inhibit the firing of a transition. Inhibitor arcs force
that the transition may only fire when the place is empty. an order of
transitions restrict the firing, so that an transition may fire only if it has
the highest priority of all enabled transitions. This concept is shown to be
compatible with reconfigurable Petri nets
Decision Problems for Petri Nets with Names
We prove several decidability and undecidability results for nu-PN, an
extension of P/T nets with pure name creation and name management. We give a
simple proof of undecidability of reachability, by reducing reachability in
nets with inhibitor arcs to it. Thus, the expressive power of nu-PN strictly
surpasses that of P/T nets. We prove that nu-PN are Well Structured Transition
Systems. In particular, we obtain decidability of coverability and termination,
so that the expressive power of Turing machines is not reached. Moreover, they
are strictly Well Structured, so that the boundedness problem is also
decidable. We consider two properties, width-boundedness and depth-boundedness,
that factorize boundedness. Width-boundedness has already been proven to be
decidable. We prove here undecidability of depth-boundedness. Finally, we
obtain Ackermann-hardness results for all our decidable decision problems.Comment: 20 pages, 7 figure
Abridged Petri Nets
A new graphical framework, Abridged Petri Nets (APNs) is introduced for
bottom-up modeling of complex stochastic systems. APNs are similar to
Stochastic Petri Nets (SPNs) in as much as they both rely on component-based
representation of system state space, in contrast to Markov chains that
explicitly model the states of an entire system. In both frameworks, so-called
tokens (denoted as small circles) represent individual entities comprising the
system; however, SPN graphs contain two distinct types of nodes (called places
and transitions) with transitions serving the purpose of routing tokens among
places. As a result, a pair of place nodes in SPNs can be linked to each other
only via a transient stop, a transition node. In contrast, APN graphs link
place nodes directly by arcs (transitions), similar to state space diagrams for
Markov chains, and separate transition nodes are not needed.
Tokens in APN are distinct and have labels that can assume both discrete
values ("colors") and continuous values ("ages"), both of which can change
during simulation. Component interactions are modeled in APNs using triggers,
which are either inhibitors or enablers (the inhibitors' opposites).
Hierarchical construction of APNs rely on using stacks (layers) of submodels
with automatically matching color policies. As a result, APNs provide at least
the same modeling power as SPNs, but, as demonstrated by means of several
examples, the resulting models are often more compact and transparent,
therefore facilitating more efficient performance evaluation of complex
systems.Comment: 17 figure
Algebraic Structure of Combined Traces
Traces and their extension called combined traces (comtraces) are two formal
models used in the analysis and verification of concurrent systems. Both models
are based on concepts originating in the theory of formal languages, and they
are able to capture the notions of causality and simultaneity of atomic actions
which take place during the process of a system's operation. The aim of this
paper is a transfer to the domain of comtraces and developing of some
fundamental notions, which proved to be successful in the theory of traces. In
particular, we introduce and then apply the notion of indivisible steps, the
lexicographical canonical form of comtraces, as well as the representation of a
comtrace utilising its linear projections to binary action subalphabets. We
also provide two algorithms related to the new notions. Using them, one can
solve, in an efficient way, the problem of step sequence equivalence in the
context of comtraces. One may view our results as a first step towards the
development of infinite combined traces, as well as recognisable languages of
combined traces.Comment: Short variant of this paper, with no proofs, appeared in Proceedings
of CONCUR 2012 conferenc
Two Algebraic Process Semantics for Contextual Nets
We show that the so-called 'Petri nets are monoids' approach initiated by Meseguer and Montanari can be extended from ordinary place/transition Petri nets to contextual nets by considering suitable non-free monoids of places. The algebraic characterizations of net concurrent computations we provide cover both the collective and the individual token philosophy, uniformly along the two interpretations, and coincide with the classical proposals for place/transition Petri nets in the absence of read-arcs
Subtyping for Hierarchical, Reconfigurable Petri Nets
Hierarchical Petri nets allow a more abstract view and reconfigurable Petri
nets model dynamic structural adaptation. In this contribution we present the
combination of reconfigurable Petri nets and hierarchical Petri nets yielding
hierarchical structure for reconfigurable Petri nets. Hierarchies are
established by substituting transitions by subnets. These subnets are
themselves reconfigurable, so they are supplied with their own set of rules.
Moreover, global rules that can be applied in all of the net, are provided
On the Enforcement of a Class of Nonlinear Constraints on Petri Nets
International audienceThis paper focuses on the enforcement of nonlinear constraints in Petri nets. First, a supervisory structure is proposed for a nonlinear constraint. The proposed structure consists of added places and transitions. It controls the transitions in the net to be controlled only but does not change its states since there is no arc between the added transitions and the places in the original net. Second, an integer linear programming model is proposed to transform a nonlinear constraint to a minimal number of conjunc-tive linear constraints that have the same control performance as the nonlinear one. By using a place invariant based method, the obtained linear constraints can be easily enforced by a set of control places. The control places consist to a supervisor that can enforce the given nonlinear constraint. On condition that the admissible markings space of a nonlinear constraint is non-convex, another integer linear programming model is developed to obtain a minimal number of constraints whose disjunctions are equivalent to the nonlinear constraint. Finally, a number of examples are provided to demonstrate the proposed approach
- …