A Petri net model for probabilistic logic

In this article we investigate the use of Petri nets for the representation of possible worlds in probabilistic logic. We propose a method to generate possible worlds based upon the reachability tree of the Petri net model. The number of columns in the matrix of possible worlds grows exponentially with the problem size. Nilsson [Proceedings of 1976 National Computer Conference and Readings in Artificial Intelligence, Morgan Kaufmann, Los Altos, CA, 1981, pp. 192-199] suggested a method to generate only those columns of the possible world matrix that are likely to be important for the solution. We provide Petri net models for the method suggested by Nilsson and show that they lead to intuitive and simple computational methods. © 1996 John Wiley & Sons, Inc.     

A logic for reasoning with inconsistency

Most known computational approaches to reasoning have problems when facing inconsistency, so they assume that a given logical system is consistent. Unfortunately, the latter is difficult to verify and very often is not true. It may happen that addition of data to a large system makes it inconsistent, and hence destroys the vast amount of meaningful information. We present a logic, called APC (annotated predicate calculus; cf. annotated logic programs of [4, 5]), that treats any set of clauses, either consistent or not, in a uniform way. In this logic, consequences of a contradiction are not nearly as damaging as in the standard predicate calculus, and meaningful information can still be extracted from an inconsistent set of formulae. APC has a resolution-based sound and complete proof procedure. We also introduce a novel notion of epistemic entailment and show its importance for investigating inconsistency in predicate calculus as well as its application to nonmonotonic reasoning. Most importantly, our claim that a logical theory is an adequate model of human perception of inconsistency, is actually backed by rigorous arguments.A preliminary report on this research appeared in LICS'89.Work of M. Kifer was supported in part by the NSF grants DCR-8603676, IRI-8903507.Work of E. L. Lozinskii was supported in part by Israel National Council for Research and Development under the grants 2454-3-87, 2545-2-87, 2545-3-89 and by Israel Academy of Science, grant 224-88.     

A generalized fuzzy Petri net model

The paper proposes a new model of Petri nets based on the use of logic based neurons. In contrast to the existing generalizations, this approach is aimed at neural-type modeling of the entire concept with a full exploitation of the learning capabilities of the processing units being used there. The places and transitions of the net are represented by OR and AND-type and DOMINANCE neurons, respectively. A correspondence between this model and the previous two-valued counterpart is also revealed. The learning aspects associated with the nets are investigated     

FPN并行反向推理算法研究

通过对Petri网模型和专家系统推理方法的研究,建立了模糊Petri网（FPN）推理模型。在此基础上提出了专家系统的FPN反向推理算法。最后通过实例对算法进行了检验,结果表明该算法具有解决复杂问题专家系统的并行推理能力,推理效率高,推理过程简单,容易实现。     

A discrete Petri net model for cephalostatin-induced apoptosis in leukemic cells

Understanding the mechanisms involved in apoptosis has been an area of extensive study due to its critical role in the development and homeostasis of multi-cellular organisms. Our special interest lies in understanding the apoptosis of tumor cells which is mediated by novel potential drugs. Cephalostatin 1 is a marine compound that can induce apoptosis in leukemic cells in a dose- and time-dependent manner even at nano-molar concentrations using a recently discovered pathway that excludes the receptor-mediated pathway and which includes both the mitochondrial and endoplasmic reticulum pathways (Dirsch et al., Cancer Res 63:8869–8876, 2003; López-Antón et al., J Biol Chem 28:33078–33086, 2006). In this paper, the methods and tools of Petri net theory are used to construct, analyze, and validate a discrete Petri net model for cephalostatin 1-induced apoptosis. Based on experimental results and literature search, we constructed a discrete Petri net consisting of 43 places and 59 transitions. Standard Petri net analysis techniques such as structural and invariant analyses and a recently developed modularity analysis technique using maximal abstract dependent transition sets (ADT sets) were employed. Results of these analyses revealed model consistency with known biological behavior. The sub-modules represented by the ADT sets were compared with the functional modules of apoptosis identified by Alberghina and Colangelo (BMC Neurosci 7(Suppl 1):S2, 2006).     

模糊空间Petri网的规则表示及动态推理

为便于表示模糊空间Petri网的状态变迁规则,根据空间关联影响区域分布现实特点,提出了空间模糊Petri网中的状态关联影响规则、变迁关联影响规则和多阈值激活规则。依据模糊产生式规则的特点,详细描述了10种具体的推理规则和表示组件,并以实例加以说明。在此基础上,结合模糊空间Petri网的特点提出了动态推理过程算法,可以实现各种空间状态规则因子的转化。动态推理的过程不仅可以获取某种“结果”,而且可以挖掘基于空间位置关联的中间状态及引起中间状态变化的事件,可以有效地指导风险过程预测和控制。     

A Petri net model for membrane systems with dynamic structure

We consider membrane systems with dissolving and thickening reaction rules. Application of these rules entails a dynamical change in the structure of a system during its evolution. First we provide a precise operational model for these dynamic membrane systems in which also promoter and inhibitor rules may occur. Next we describe a translation into behaviourally equivalent Petri nets with localities and range arcs.     

A novel cause analysis approach of grey reasoning Petri net based on matrix operations

Cause analysis makes great contributions to identifying the priorities of the causes in fault diagnosis system. A fuzzy Petri net (FPN) is a preferable model for knowledge representation and reasoning and has become an effective fault diagnosis tool. However, the existing FPN has some limitations in cause analysis. It is criticized for the inability to fully consider incomplete and unknown knowledge in uncertain situations. In this paper, an enhanced grey reasoning Petri net (EGRPN) based on matrix operations is presented to address the limitations and improves the flexibility of the existing FPN. The proposed EGRPN model uses grey numbers to handle the greyness and inaccuracy of uncertain knowledge. Then, the EGRPN inference algorithm is executed based on the matrix operations, which can express the relevance of uncertain events in the form of grey numbers and improve the reliability of the knowledge reasoning process. Finally, industrial examples of cause diagnosis are used to illustrate the feasibility and reliability of the EGRPN model. The experimental results show that the new EGRPN model is promising for cause analysis.

     

A fuzzy Petri net model to estimate train delays

Even with the most accurate timetable, trains often operate with delays. The running and waiting times for trains can increase unexpectedly, creating primary delays that cause knock-on delays and delays for other trains. The accurate estimation of train delays is important for creating timetables, dispatching trains, and planning infrastructures. In this work, we proposed a fuzzy Petri net (FPN) model for estimating train delays. The FPN model with characteristics of hierarchy, colour, time, and fuzzy reasoning was used to simulate traffic processes and train movements in a railway system. The trains were coloured tokens, the track sections were termed places, and discrete events of train movement were termed transitions. The train primary delays were simulated by a fuzzy Petri net module in the model. The fuzzy logic system was incorporated in the FPN module in two ways. First, when there were no historical data on train delays, expert knowledge was used to define fuzzy sets and rules, transforming the expertise into a model to calculate train delays. Second, a model based on the Adaptive Network Fuzzy Inference System (ANFIS) was used for systems where the historical data on train delays were available (from detection systems or from the train dispatcher’s logs). The delay data were used to train the neuro-fuzzy ANFIS model. After the results of the fuzzy logic system were verified, the ANFIS model was replicated by a fuzzy Petri net. The simulation was validated by animating the train movement and plotting the time-distance graph of the trains. Results of the simulation were exported to a database for additional data mining and comparative analysis. The FPN model was tested on a part of the Belgrade railway node.     

基于面向对象Petri网的动态合同网协议通用模型

传统的合同网协议模型通过管理Agent和承包商Agent之间招投标进行交互和协商以共同完成目标任务。但传统合同网协议模型也存在一些如协作过程中通信量大、通用性不强等问题。为此，采用面向对象Petri网，引入对象Agent，对动态合同网协议进行建模,并采用Petri网的数学分析方法对模型进行了分析，表明模型具有通用性、并发性、活性的特点且通信量减少。     

An extended Petri net model for normal logic programs

This paper presents an application of the concepts of siphons (deadlocks) and inhibitor arcs in Petri net theory to logic programs with negations. More specifically, an extended Petri net is used to model function-free normal logic programs. In this model, because of the presence of inhibitor arcs, the arbitrary applications of firing rule may cause a contradictory situation. We suggest two directions to avoid contradictions: greedy and secure applications of firing rule. We choose the secure application and show that this is a direct translation of the well-founded semantics in the net model. Furthermore, we show that the greatest unfounded set corresponds to the greatest siphon in Petri net theory when we delete the transitions disabled by the secure application of firing rule, and that the property of siphon simplifies the computation of well-founded semantics for logic programs. We also propose the reduced-Petri-net method by which we can reduce an extended Petri net to a Petri net without inhibitor arcs and compute the well-founded model by iterative applications of this transformation using conventional application of firing rule     

A Petri net model for integrated process and job shop production planning

In this paper a new Petri net class (Chameleon systems) for modeling and analyzing joined process planning and job shop production planning is proposed based on the multi-level Petri net model introduced by Valk (1995). Chameleon system is a High-level Petri net extended with time that consists of a High-level Petri net modeling the workshop which is called system net and ordinary Petri net modeling the jobs and setups which act as tokens of the system net and therefore are called token nets. Process plans of the jobs are partial orders of operation groups and alternatives. The uncertainty of operation duration is captured by a new time model. The advantages of this new modeling approach are the following: (i) a modular construction of the joined process and job shop planning is allowed, (ii) classical known Petri net analysis methods can be applied and (iii) the analysis can be done at different levels of abstraction.     

A dynamic Petri net model for iterative and interactive distributed multimedia presentation

Object Composition Petri Nets, Priority Petri Nets, Dynamic OCPN, and Enhanced P-Nets have extended the original Petri Net to achieve the modeling of media synchronization and asynchronous user interactions during multimedia playback. The dynamic Petri Net (DPN) has been conceptualized to tackle existing problems in these two areas of modeling distributed multimedia systems. DPN features dynamic modeling elements which allows iteration and hence is able to reduce graph sizes of synchronous playback models while allowing greater details to be shown. DPN also introduces asynchronous event handling techniques that are powerful and effective. DPN was used in the design and modeling of a multimedia orchestration tool which is a typical representation of an application that works in a distributed multimedia system.     

基于逻辑Petri网的Web服务簇模型

在基于聚类的Web服务中,同一服务簇中的服务在参数名称、参数数量和顺序方面不尽一致,具有参数不确定性的特点,导致参数匹配仍需要很大的工作量。因此提出一种基于逻辑Petri网的Web服务簇模型,将服务的参数集合表示为基于服务簇参数集的逻辑向量,建立了服务簇到各个服务的映射关系,实现对服务参数的统一管理。基于语义相似度的参数匹配仅在服务簇层进行,在服务簇内可以用位置向量直接定位参数,通过逻辑比较判断是否匹配,使得参数匹配的规模和计算复杂度大大降低,提高了服务发现效率。     

基于着色Petri网的工作流模型研究

针对传统Petri网建模方法的不足,研究了通过资源结构建模的工作流建模方法.在着色Petri网的基础上提出资源/任务网(R/T-net),并给出基于R/T-net的工作流建模过程.R/T模型能够有效地实现产品数据结构和过程结构的统一,资源流对任务流的控制以及模型的仿真.     

基于Perti网的工作流访问控制模型研究

提出了一种工作流访问控制模型WACM(Workflow Access Control Model),该模型支持基于角色的授权,通过工作流引擎中的访问控制矩阵进行同步授权,采用Perti网来描述工作流,对工作流参考模型进行了定义和描述,分析了工作流访问控制模型WACM的体系结构,并将该模型应用到电子商务工作流中,建立了基于安全电子商务协议(SET)的访问控制模型。