共查询到18条相似文献,搜索用时 140 毫秒
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一类Petri网系统的活性 总被引:2,自引:0,他引:2
Petri网是一种用来研究具有异步、并发特征的离散事件系统的合适的工具,当用Petri网来模拟一个实际系统时,关心的问题之一就是要确定这个Petri网模型是否具有一些所期望的特生,如活性、有界性等,这些特性均是系统的重要动态行为,该文基于文献[1]给出了Petri网的一子类,即弱化非自控网(Weak Extended Non SelfControlling Nets,简称WENSeC网),该类网覆盖了扩展自由选择网和扩展非自控网,文中提出了并证明了WENSeC网系统活性的的充分必要条件满足死锁-陷阱性质,同时对WENSeC网的一子类,通过转化方法,证明了该类结构有界网的结构活判定算法可借用扩非自控网的有关结果也是多项式时间算法。 相似文献
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结构活性作为Petri网的重要结构性质,在Petri网活性判定领域具有较高的研究价值。从Petri网有向回路对结构活性的影响入手,分析与判定无冲突Petri网的结构活性,讨论库所元素及其后置变迁之间是否存在有向回路对Petri网结构活性的影响,研究该类Petri网结构活性判定方法的相关条件与结论,得到无冲突Petri网是满足结构活性的充分必要条件。分析结果表明,该判定方法可在多项式时间内判定无冲突Petri网的结构活性。 相似文献
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基于Petri网语言的并发系统性质研究 总被引:4,自引:1,他引:3
给出Petri网弱活性(无死锁)与活性的两个语言刻画,讨论了同步合成Petri网的语言性质,基于Petri网语言,给出了判定Petri网活性的充分必要条件。同时研究了Petri网同步合成过程中活性保持问题,给出保持活性的充分必要条件。这些结果为讨论网的活性测试和控制提供了形式语言的方法。 相似文献
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针对柔性制造系统的设计和分析,提出了经由Petri网共享子网构成合成网的解决方案;研究了Petri网共享子网合成的动态性质保持问题,给出了合成网保持活性、有界性的一组充分条件;对一个柔性制造系统进行了设计和分析。本文的结果可为Petri网系统静态和动态性质的考察提供有效途径,为Petri网复杂大系统的分析提供重要手段,并特别适合于柔性制造系统的设计,具有一定的实用价值。 相似文献
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活性和有界性是网系统的重要行为特性.从分解以及尽可能简单分解的角度得到了非对称选择网的一个子类,可分解非对称选择网(简称DAC网),证明了DAC网系统活性的充分必要条件,同时给出了DAC网系统活性有界性的充分必要条件,也进一步讨论了判定一个Petri网系统是否是活的有界的DAC网系统的多项式算法. 相似文献
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结合医院病房监护系统的问题描述,给出了系统的监护流程图,在流程的基础上建立了相应的Petri网模型。最后对该模型进行可达性、安全性、有界性和活性四个主要的性质进行分析。 相似文献
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可重写Petri网:位置可重写及性质分析 总被引:1,自引:0,他引:1
针对Petri网对动态系统重构形式化描述和建模能力的不足,提出了可重写Petri网和位置可重写Petri网的基本概念.分析了位置可重写Petri网保持有界性、保守性、可重复性及活性等性质.给出了位置可重写Petri网保持活性的一个充要条件.证明了共享合成Petri网是位置可重写Petri网的一个实例,建立了退化的位置可重写Petri网模拟共享合成Petri网的算法.所得结果能够为动态重构系统的Petri网形式化建模提供理论方法,为大规模动态分布式系统的形式化验证提供有效途径. 相似文献
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Petri网的TT型子网精细化操作性质分析及其应用 总被引:1,自引:0,他引:1
针对企业用加工厂或车间加工某种产品等这一类业务处理问题,提出了用Petri网精细化操作解决问题的方案。定义了一种TT-型子网,用这种子网分别对Petri网系统中的某些变迁进行细化,得到更细致、更精确的Petri网系统。研究了Petri网精细化操作的动态性质保持问题,给出这种精细化操作保持活性、有界性、可回复性和公平性的充要条件;本文的结果可为Petri网系统静态和动态性质的考察提供有效途径,为Petri网复杂大系统的分析提供重要手段,并特别适合于一类业务系统的描述和处理,具有一定的实用价值。 相似文献
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Supervisory controller design to enforce boundedness, liveness, and reversibility in Petri nets is considered. The Petri nets considered may have non-unity weight arcs and both controllable and uncontrollable transitions. Algorithms for a centralized controller design approach are first developed. The developed algorithms always find a controller whenever it exists. This controller enforces boundedness, liveness, and reversibility; it also avoids deadlock. Furthermore, it is shown that the controller obtained is the least restrictive controller among all controllers which enforce desired properties. A decentralized controller design approach, based on overlapping decompositions, is then introduced. Algorithms to design decentralized controllers based on this approach are also developed. These controllers, when they exist, also guarantees boundedness, liveness, reversibility and deadlock freeness. The decentralized controllers have two main advantages over the centralized ones. First, they have reduced on-line computation and communication requirements. Second, the computational time required to design decentralized controllers is considerably less than that required for centralized controllers. 相似文献
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Liveness is one of the most important properties of the Petri net analysis. This property is concerned with a capability for firing of transitions. On the other hand, place-liveness is another notion related to liveness, which is concerned with a capability for having tokens in places. Concerning these liveness and place-liveness problems, this paper suggests a new subclass of Petri net, ‘POC nets’, as a superclass of AC nets and DC nets. For this subclass, the equivalence between liveness and place-liveness is shown and a sufficient condition for liveness for this POC net is derived. Then the results are extended to liveness problem of timed Petri nets which have transitions with finite firing durations and the earliest firing rule. Although liveness of a (non-timed) Petri net is neither necessary nor sufficient condition for liveness of a timed Petri net, it is shown that liveness is preserved if the net has POC structure. Furthermore, it is pointed out that if a POC net satisfies some additional condition, Petri net liveness is equivalent to timed Petri net liveness. Finally, it is shown that liveness of timed POC nets with TC structure and the earliest firing rule is decidable with deterministic polynomial time complexity. 相似文献
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Petri网共享T型子网合成结构性质分析及其应用 总被引:1,自引:0,他引:1
为了解决系统设计中的子系统共享问题,提出了经由Petri网共享T-型子网构成共享T-型子网合成网的解决方案;研究了共享T-型子网合成网的结构性质,提出了共享T-型子网合成网保持结构有界性、守恒性、可重复性、相容性、P-不变量、T-不变量、公平性和结构活性的充分条件或充要条件;特别在证明结构活性保持性的过程中,体现了Petri网层次化的描述方法。本文的结果可为Petri网系统合成性质的考察提供有效途径,为复杂大系统的分析提供重要手段,并特别适合于一类系统的设计和分析,具有一定的实用价值。 相似文献
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Fei-Yue Wang Yanqing Gao MengChu Zhou 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2004,34(1):303-308
Reachability trees, especially the corresponding Karp-Miller's finite reachability trees generated for Petri nets are fundamental for systematically investigating many characteristics such as boundedness, liveness, and performance of systems modeled by Petri nets. However, too much information is lost in a FRT to render it useful for many applications. In this paper, modified reachability trees (MRT) of Petri nets are introduced that extend the capability of Karp-Miller's FRTs in solving the liveness, deadlock, and reachability problems, and in defining or determining possible firing sequences. The finiteness of MRT is proved and several examples are presented to illustrate the advantages of MRT over FRT. 相似文献
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ST—组合Petri网的结构性质分析 总被引:2,自引:0,他引:2
本文提出ST-组合Petri网的概念,讨论了ST-组合Petri网对子网的结构性质保持问题,深入研究了ST-组合Petri网的结构活性、结构有界性,守恒性,可重复性,相容性,公平性。本文给出的网组合可作为系统合成与分析的有效方法。 相似文献
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H.M.W. Verbeek M.T. Wynn W.M.P. van der Aalst A.H.M. ter Hofstede 《Journal of Computer and System Sciences》2010,76(2):125-143
Reset/inhibitor nets are Petri nets extended with reset arcs and inhibitor arcs. These extensions can be used to model cancellation and blocking. A reset arc allows a transition to remove all tokens from a certain place when the transition fires. An inhibitor arc can stop a transition from being enabled if the place contains one or more tokens. While reset/inhibitor nets increase the expressive power of Petri nets, they also result in increased complexity of analysis techniques. One way of speeding up Petri net analysis is to apply reduction rules. Unfortunately, many of the rules defined for classical Petri nets do not hold in the presence of reset and/or inhibitor arcs. Moreover, new rules can be added. This is the first paper systematically presenting a comprehensive set of reduction rules for reset/inhibitor nets. These rules are liveness and boundedness preserving and are able to dramatically reduce models and their state spaces. It can be observed that most of the modeling languages used in practice have features related to cancellation and blocking. Therefore, this work is highly relevant for all kinds of application areas where analysis is currently intractable. 相似文献
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We consider the complexity of several standard problems for various classes of Petri nets. In particular, the reachability problem, the liveness problem and the k-boundedness problems are analyzed. Some polynomial time and polynomial space complete problems for Petri nets are given. We then show that the problem of deciding whether a Petri net is persistent is reducible to reachability, partially answering a question of Keller. Reachability and boundedness are proved to be undecidable for the Time Petri net introduced by Merlin. Also presented is the concept of controllability, i.e., the capability of a set of transitions to disable a given transition. We show that the controllability problem requires exponential space, even for 1-bounded nets. 相似文献