A generalized net model of a client/server multiagent system with agent tracking

This paper proposes a methodology for developing multi-agent systems. Several design considerations for robotic agents are discussed. A script specifies a multi-agent system by defining the behavior of each agent. An agent is modeled by an extended finite state automaton. By using the state transition rules as the building blocks, an agent as well as a multi-agent system can be developed efficiently. This methodology is further applied to multi-agent robotic systems in which reactivity and interaction are important issues. A script-based architecture is developed to implement the agents in multi-agent robotic systems. This architecture considers not only the control architecture of a single agent, but also the interactions among multiple agents and their environments. A script for the object-sorting task problem is utilized for demonstration.

The development of multi-agent technologies and their widespread implementation in distributed computer systems is due to the properties of autonomy, mobility, intelligence and cooperativity, which provide power and flexibility in solving distributed, dynamic, fuzzy problems. At the same time, it is precisely these characteristic properties of multi-agent systems, that require special measures to ensure their operability and reliability of functioning, especially in the case of critical use. The proposed model for verifying the properties of dynamic communication is based on extended Petri nets and automata behavioral check and recognition experiments. Verification of two-tier and multi-tier communications of arbitrary spatial and temporal topology includes behavioral check of the mechanisms of conditions, preparation, transmission, buffering, broadcasting, taking into account probabilistic-temporal, group and concurrent characteristics. The verification model of agent commutation is designed to determine the conditions for analyze, check and recognizing of agent interactions in diagnostic methods for distributed multi-agent systems and allows to reduce the computational complexity of analysis, check and recognition of behavior of multi-agent systems.

A New Approach In Learning For Intelligent Multi Agent Systems

Many researchers focus on resource intensive tasks which have to be run continuously over long periods. A Grid may offer resources for these tasks, but they are contested by multiple client agents. Hence, a Grid might be unwilling to allocate its resources for long terms, leading to tasks’ interruptions. This issue becomes more substantial when tasks are data inter-dependent, where one interrupted task may cause an interruption of a bundle of other tasks. In this paper, we discuss a new resource re-allocation strategy for a client, in which resources are re-allocated between the client tasks in order to avoid prolonged interruptions. Those re-allocations are decided by a client agent, but they should be agreed with a Grid and can be performed only by a Grid. Our strategy has been tested within different Grid environments and noticeably improves client utilities in almost all cases.

An increase in volumes of data and a shift towards live data enabled a stronger focus on resource-intensive tasks which run continuously over long periods. A Grid has potential to offer the required resources for these tasks, while considering a fair and balanced allocation of resources among multiple client agents. Taking this into account, a Grid might be unwilling to allocate its resources for long time, leading to task interruptions. This problem becomes even more serious if an interruption of one task may lead to the interruption of dependent tasks. Here, we discuss a new strategy for resource re-allocation which is utilized by a client with the aim to prevent too long interruptions by re-allocating resources between its own tasks. Those re-allocations are suggested by a client agent, but only a Grid can re-allocate resources if agreed. Our strategy was tested under the different Grid settings, accounting for the adjusted coefficients, and demonstrated noticeable improvements in client utilities as compared to when it is not considered. Our experiment was also extended to tests with environmental modelling and realistic Grid resource simulation, grounded in real-life Grid studies. These tests have also shown a useful application of our strategy.

In this paper, we present a multi-agent information system model that can deal with complex multi-activity information-driven tasks. After defining a single information agent architecture in an abstract way, we describe the multi-agent model (called the parallel model), as well as a simple collaboration protocol for the multiple activity information agents. Experimental results are presented with the multi-agent system that demonstrate that a significantly larger number of relevant documents can be retrieved through collaboration than what is possible with decoupled agents. Hence, such multi-agent parallel models appear to hold considerable promise in providing the user with high quality information services in a variety of business and scientific information-driven tasks.

Network traffic data are critical for network research. With the help of synthetic traffic, researchers can readily generate data for network simulation and performance evaluation. However, the state-of-the-art traffic generators are either too simple to generate realistic traffic or require the implementation of original applications and user operations. We propose Synthetic PAcket Traffic Generative Adversarial Networks (SPATGAN) that are capable of generating synthetic traffic. The framework includes a server agent and a client agent, which transmit synthetic packets to each other and take the opponent's synthetic packets as conditional labels for the built-in Timing Synthesis Generative Adversarial Networks (TSynGAN) and a Packet Synthesis Generative Adversarial Networks (PSynGAN) to generate synthetic traffic. The evaluations demonstrate that the proposed framework can generate traffic whose distribution resembles real traffic distribution.

SPN as a tool for risk modeling of fires in process industries

The unfolding technique is an efficient tool to explore the runs of a Petri net in a true concurrency semantics, i.e. without constructing all the interleavings of concurrent actions. But even small real systems are never modeled directly as ordinary Petri nets: they use many high-level features that were designed as extensions of Petri nets. We focus here on two such features: colors and compositionality. We show that the symbolic unfolding of a product of colored Petri nets can be expressed as the product of the symbolic unfoldings of these nets. This is a necessary result in view of distributed computations based on symbolic unfoldings, as they have been developed already for standard unfoldings, to design modular verification techniques, or modular diagnosis procedures, for example. The factorization property of symbolic unfoldings is valid for several classes of colored or high-level nets. We derive it here for a class of (high-level) open nets, for which the composition is performed by connecting places rather than transitions.

Modeling computer software, hardware, and other systems using Petri nets is discussed. The various analysis techniques and extension of Petri nets are considered. Problems in Petri net analysis techniques are examined, and analysis techniques that solve them are given.

The paper deals with reconfigurable embedded control systems following different component-based technologies and/or Architecture Description Languages used today in industry. We define a Control Component as a software unit to support control tasks of the system, which is assumed to be a network of components with precedence constraints. We define an agent-based architecture to handle automatic reconfigurations under well-defined conditions by creating, deleting, or updating components to bring the whole system into safe and optimal behaviors. To cover all possible reconfiguration forms, we model the agent by nested state machines according to the formalism Net Condition/Event Systems (NCESs), which is an extension of Petri nets. In addition, we apply a model checking to verify functional and extra-functional properties according to the temporal logic "Computation Tree Logic” (CTL). The goal is to check the agent reactivity after any evolution of the environment. Several complex networks can implement the system, where each one is executed at a given time when a corresponding reconfiguration scenario is automatically applied by the agent. To check the correctness of each one of them, we apply in several steps a refinement-based approach that automatically specifies feasible Control Components according to NCES. The model checker SESA is automatically applied in each step to verify deadlock properties of new generated components, and it is manually used to verify CTL-based properties according to user requirements. We implement the reconfiguration agent by three modules that allow interpretations of environment evolutions, decisions of useful reconfiguration scenarios, and finally, their applications. Two Industrial Benchmark Production Systems FESTO and EnAS available in our research laboratory are applied to explain the contributions of the paper.

In this paper, we propose the new method for the parallel system design based on expanded the logical coloured Petri net (LCPN). An LCPN is an extended Petri net that solves the problem of system description in previously proposed place/transition nets and coloured Petri nets. This extension of Petri nets is suitable for designing complex control systems and for discussing methods of evaluating such systems realistically. In order to study the behaviour of the server system modelled with this net we simulated a Java program. This program confirmed that this extended Petri net is an effective tool for modelling the parallel system.

With the growing use of UML diagrams for software architecture description and the importance of non-functional requirements evaluation at software architecture level, filling the scientific gap between architect and requirement analyst is considered to be significant. Software architects are not usually familiar with non-functional requirement analysis and are not able to analyze such requirements easily. On the other hand, non-functional requirements cannot be evaluated directly by UML diagrams. Therefore, the architect should annotate additional information of the nonfunctional requirements to software architecture description and then an executable model can be produced. These executable models can be petri nets, queuing networks, stochastic process algebra and etc. One kind of the UML diagrams that can be used to describe software architecture is component diagram. In this paper, we propose a new algorithm that enables an architect to transform a component diagram into an executable model based on different extensions of petri nets. Moreover, we show how to use this petri net model for performance evaluation and simulation and the implications of this transformation are described completely. Finally, to represent the usage of our proposed algorithm, we consider a case study as an example.

An algorithm is introduced for solving multiprocess scheduling problems, based on an extension of Petri nets (PNs) able to cope both with multiple processes and with time constraints. These nets are called timed colored PNs (TCPNs). The class of problems faced by the approach can be characterized as follows: there is a set of concurrent processes, each formed by a number of temporally related tasks (segments). Tasks are executable by alternate resource sets different both in performance and costs. Processes and tasks are characterized by release times, due dates, and deadlines. Time constraints are also present in the availability of each resource in resource sets. It has been proved that the problem does not admit an algorithm for an optimal solution in polynomial time. The proposed algorithm finds a suboptimal schedule according to a set of optimization criteria, based on the tasks' and processes' times (earliness, tardiness) and/or on the time-independent resources' costs. >

This paper describes the use of PROTEAN and associated methodology to verify the ISO FTAM (File Transfer, Access and Management) DIS (Draft international standard) protocol and discusses the analysis of its behaviour using PROTEAN facilities. PROTEAN is an automated validation tool developed by Telecom Australia. The formal description technique used is Numerical Petri Nets (NPNs), an extension of Petri Nets. The procedures carried out were based primarily on reachability analysis. The behaviour of the protocol as specified was compared to its service specification. There are two protocol machines specified for FTAM: the basic protocol and the error recovery protocol machines.