Petri net

About: Petri net is a research topic. Over the lifetime, 25039 publications have been published within this topic receiving 406994 citations.

A Region-Based Algorithm for Discovering Petri Nets from Event Logs

Abstract: The paper presents a new method for the synthesis of Petri nets from event logs in the area of Process Mining. The method derives a bounded Petri net that over-approximates the behavior of an event log. The most important property is that it produces a net with the smallest behavior that still contains the behavior of the event log. The methods described in this paper have been implemented in a tool and tested on a set of examples.

Knowledge Acquisition and Representation Using Fuzzy Evidential Reasoning and Dynamic Adaptive Fuzzy Petri Nets

Abstract: The two most important issues of expert systems are the acquisition of domain experts' professional knowledge and the representation and reasoning of the knowledge rules that have been identified. First, during expert knowledge acquisition processes, the domain expert panel often demonstrates different experience and knowledge from one another and produces different types of knowledge information such as complete and incomplete, precise and imprecise, and known and unknown because of its cross-functional and multidisciplinary nature. Second, as a promising tool for knowledge representation and reasoning, fuzzy Petri nets (FPNs) still suffer a couple of deficiencies. The parameters in current FPN models could not accurately represent the increasingly complex knowledge-based systems, and the rules in most existing knowledge inference frameworks could not be dynamically adjustable according to propositions' variation as human cognition and thinking. In this paper, we present a knowledge acquisition and representation approach using the fuzzy evidential reasoning approach and dynamic adaptive FPNs to solve the problems mentioned above. As is illustrated by the numerical example, the proposed approach can well capture experts' diversity experience, enhance the knowledge representation power, and reason the rule-based knowledge more intelligently.

A Light Workflow Management System Using SimpleProcess Models

Abstract: Workflow management systems are considered a hot technology. Nevertheless, up to now they have not had the diffusion other packages such as productivity tools, E-mail systems and groupware platforms have. We believe that this fact is due to the many limitations of current workflow technology (weak support for changes; complex exception handling mechanisms; limited openness to and integrability with other system componentss …) and that radically new workflow management systems should be designed and developed in order to offer adequate products to the market. In this paper, we outline the main innovative features of the workflow management component of the Milano system making it highly flexible and adaptable. Particular attention is paid to its modelling framework, which is based on a class of net systems well supported by efficient algorithms, and to the services it offers to both workflow designers and actors. The most relevant aspects of the MILANO workflow management system are also illustrated through a realistic example.

Contextual Petri nets, asymmetric event structures, and processes

Abstract: We present an event structure semantics for contextual nets, an extension of P/T Petri nets where transitions can check for the presence of tokens without consuming them (read-only operations). A basic role is played by asymmetric event structures, a generalization of Winskel's prime event structures where symmetric conflict is replaced by a relation modelling asymmetric conflict or weak causality, used to represent a new kind of dependency between events arising in contextual nets. Extending Winskel's seminal work on safe nets, the truly concurrent event-based semantics of contextual nets is given at categorical level via a chain of coreflections leading from the category SW-CN of semi-weighted contextual nets to the category Dom of finitary prime algebraic domains. First an unfolding construction generates from a contextual net a corresponding occurrence contextual net, from where an asymmetric event structure is extracted. Then the configurations of the asymmetric event structure, endowed with a suitable order, are shown to form a finitary prime algebraic domain. We also investigate the relation between the proposed unfolding semantics and several deterministic process semantics for contextual nets in the literature. In particular, the domain obtained via the unfolding is characterized as the collection of the deterministic processes of the net endowed with a kind of prefix ordering. 2001 Elsevier Science.

Timed state space analysis of real-time preemptive systems

Abstract: A modeling notation is introduced which extends time Petri nets with an additional mechanism of resource assignment making the progress of timed transitions be dependent on the availability of a set of preemptable resources The resulting notation, which we call preemptive time Petri nets, permits natural description of complex real-time systems running under preemptive scheduling, with periodic, sporadic, and one-shot processes, with nondeterministic execution times, with semaphore synchronizations and precedence relations deriving from internal task sequentialization and from interprocess communication, running on multiple processors A state space analysis technique is presented which supports the validation of preemptive time Petri net models, combining tight schedulability analysis with exhaustive verification of the correctness of logical sequencing The analysis technique partitions the state space in equivalence classes in which timing constraints are represented in the form of difference bounds matrixes This permits it to maintain a polynomial complexity in the representation and derivation of state classes, but it does not tightly encompass the constraints deriving from preemptive behavior, thus producing an enlarged representation of the state space False behaviors deriving from the approximation can be cleaned-up through an algorithm which provides a necessary and sufficient condition for the feasibility of a behavior along with a tight estimation of its timing profile