Showing papers on "Contract Net Protocol published in 2008"

Enhancing NetLogo to Simulate BDI Communicating Agents

Abstract: The implementation process of complex agent and multi-agent systems (AMAS) can benefit significantly from a simulation platform that would allow rapid prototyping and testing of initial design ideas and choices. Such a platform, should ideally have a small learning curve, easy implementation and visualisation of the AMAS under development, while preserving agent oriented programming characteristics that would allow to easily port the design choices to a fully-fledged agent development environment. However, these requirements make such a simulation platform an ideal learning tool as well. We argue that NetLogo meets most of the requirements that suit our criteria. In addition, we describe two extra NetLogo libraries, one for BDI-like agents and one for ACL-like communication that allow effortless development of goal-oriented agents, that communicate using FIPA-ACL messages. We present one simulation scenario that employs these libraries to provide an implementation in which agents cooperate under a Contract Net protocol.

Contract Net Protocol for Coordination in Multi-Agent System

Abstract: Contract net protocol (CNP) is often used for coordination in a multi-agent system. Due to the limitations inherent in the conventional CNP, this paper proposes a norm-based CNP to improve the efficiency and effectiveness of the coordination processes in a multi-agent system. First, a three-dimensional taxonomy of norm is put forward in terms of the hierarchy, type and flexibility of norms. Then a coordination process guided by norm-based CNP is developed under the taxonomy framework. The new coordination process consists of two principal stages and five sub-divided phases, providing a feasible solution for the optimization of the candidate selection. The merits of dividing the process into two stages are converging coordination process as soon as possible and controlling whole system effectively. In coordination process, norms ensure to achieve global performance and agents pursuing maximal local performance to achieve satisfied result. Finally a case study is performed to illustrate the real application of the proposed approach.

Task allocation for multi-robot cooperative hunting behavior based on improved auction algorithm

Abstract: Within the frameworks of the well-known contract net protocol, a task allocation method for multi-robot cooperative hunting behavior is proposed based on an improved auction algorithm. Previous allocation methods using ordinary auction algorithms might turn out to be unsuitable when targets keep moving. Furthermore, the ordinary auctions might lead to unfavorable releases of the captured targets, because the hunters which were formerly assigned to relative tasks might be designated to some other tasks in a new round of bidding. In this paper an improved auction algorithm is proposed which may establish an ordered task list and holds biddings for each task in the list repeatedly. Therefore the allocation methods can be modified which allow dealing with a considerable volume of tasks in a dynamic environments. In addition, this approach holds no biddings for the accomplished tasks, and the relative hunters will keep guarding on their previously assigned target. The improvements also save the computational cost. Simulations demonstrate the flexibility and the efficiency of the method and the hunting task can be achieved in nearly half the time of the original methods.

Modelling and Analysing the Contract Net Protocol - Extension Using Coloured Petri Nets

Abstract: The Contract Net Protocol is a task allocation protocol that facilitates negotiation between bidders and an auctioneer in a Multi-Agent System to form a contract. The extension allows the bidders to interact with more than one auctioneer concurrently, and to update their bids until a bid is granted. This introduces flexibility and ensures better selection of a bid. In this paper, we model the Contract Net Protocol - extension with Coloured Petri Nets and show that it terminates correctly. We analyse the terminal states and prove that the agents have consistent beliefs at the end of the negotiations, and that there is no "dead code" in the procedures. Lastly, we show how the number of terminal states and channel bounds are related to the number of bidders.

An agent-based infrastructure for virtual enterprises using Web-Services standards.

Abstract: Nowadays, most products in the market are increasing unlikely manufactured entirely within a single company. Instead, a network of manufacturing companies, usually known as a Virtual Enterprise, is involved. Each of the companies becomes a node in the network to play a role in the value-adding process in the production cycle. In other words, a Virtual Enterprise (VE) is an ad hoc organization that combines the competencies of its partners and commits its resources flexibly to respond to business opportunities. To facilitate effective collaboration, suitable information systems that can enable VE partners to communicate and share data, information and knowledge across organizational boundaries are essential. One of the major obstacles towards achieving this goal is a lack of standardized technologies to allow partnering enterprises to publicise their services and expertise as well as locating and interacting with one another in a dynamic fashion. This paper proposes a multi-agent infrastructure to manage VEs and support XML-based agents coordination using a contract net protocol and Web Services standards. Feasible agent-based architectures for partnering enterprises are also suggested and illustrated.

Retractable contract network for empowerment in workforce scheduling

Abstract: This paper is about business modelling and negotiation protocol design in distributed scheduling, where individual agents have individual (potentially conflicting) interests. It is motivated by BT's workforce scheduling problem, in which multiple service providers have to serve multiple service buyers. The service providers and buyers all attempt to maximize their own utility. The overall problem is a multi-objective optimization problem; for example, one has to maximize completion rates and service quality and minimize travelling distances. Although the work is motivated by BT's business operations, the aim is to develop a general negotiation protocol for staff empowerment. Standard contract net is a practical strategy in distributed scheduling where agents may have conflicting objectives. In this paper, we have introduced a retractable contract net protocol, RECONNET, which supports hill-climbing in the space of schedules. It is built upon a job-release and compensation mechanism. A system based on RECONNET has been implemented for BT's workforce scheduling problem. The software, which we call ASMCR, allows the management to exert full control over the company's multiple objectives. The manager generates a Pareto set of solutions by defining, for each buyer and seller, the weights given to each objective. ASMCR gives service buyers and sellers ownership of their problem and freedom to maximize their performance under the criteria defined by the management. ASMCR was tested on real-sized problems and demonstrated to meet BT's operational time requirement. It has full potential to be further developed for tackling BT's workforce scheduling problem.

A Verification by Abstraction Framework for organizational Multi-Agent Systems

Abstract: Software agents and multi-agent systems (MAS from now on) are recognized as both abstractions and eective technologies for modelling and building complex distributed applications. However, they are still dicult to engineer. The reason is that when massive number of autonomous components interact it is very dicult to predict that the emergent organizational structure fits the system goals or that the desired functionalities will be fulfilled. Verification approaches try to evaluate whether or not a product, service, or system complies with a specification. However verification approaches are limited by the state-space of the system under study. This paper proposes an approach based upon an organizational framework and specifically the capacity concept which enables to abstract a role know-how and to reduce the state space of the system under study. A formal framework based on multi-formalisms language and the specification approach are presented and illustrated through the specification of a part of the contract net protocol.

Dynamic role binding with Agent-centric Contract Net Protocol in agent organizations

Abstract: As open multi-agents systems are getting increasing attentions in building large-scale software systems, the study on agent organizations - a building block of multi-agents systems, becomes a promising research track. Roles as a first class citizen in agent organizations impose an imperious demand for dealing with the major challenge: how agents bind roles in the formation of agent organizations in which agents can dynamically enter or leave the organizations. This challenge can be further decomposed into four issues: how to discover agents distributed over various organizations, how to select reliable agents to bind roles, how to enable agents to cooperate in roles binding, and how to unbind roles as agents leave an organization. The focus of this paper is on an extension to Contract Net protocol with reputation model to address these four issues related to the life cycle of dynamic role binding, called agent-centric contract net protocol (ACNP), as a negotiation mechanism that agents can adopt to establish agent organizations at run time through roles binding.

An Extended the Contract Net Protocol Based on the Personal Assistant

Abstract: This paper is aimed at the extended the contract net protocol (CNP) based on the personal assistant for reducing the cost of communication. The CNP is a powerful coordination mechanism in multi-agent systems. However, the performance of the CNP degrades when the number of agents increases or the announcement is of high frequency. Hence, it has a problem of applicability to large-scale multi-agent systems. In order to overcome this problem, a personal assistant that may evaluate the other agents is proposed. It can avoid an announcement sent to redundant bidders, and only the best bidder sends the bid proposal. Experimental results demonstrate that the extended CNP based on the personal assistant can reduce the cost of communication evidently.

Transshipment policy research of multi-location inventory system based on Multi-Agent System

Abstract: This paper considers a multi-location inventory system with several retailers who share one supplier. Emergent transshipments happen between retailers when in-hand inventory and pipeline stock are not enough to meet the demand. Our model based on Multi-Agent System (MAS) and game theory allows consultation and local decision making for transshipment. Contract Net protocol mechanism is applied to organize the transshipment consultation between retailers. What makes our research different is that Multi-period transshipment cooperation of retailers is considered as an unlimited repeated game and Robert Axelrodpsilas evolution theory of cooperation is brought into the transshipment cooperation. Many practical factors, such as demand lead-time, transshipment lead-time and replenishment lead-time, which make the model more complex, are also considered. The optimal inventory control policy is obtained by simulation and optimization with software Anylogic.

CNP-based Implementation of Service-oriented Workflow Mapping in SHGWMS

Abstract: ShanghaiGrid has a complex service-oriented infrastructure. Workflow management is emerging as one of the most important part of it. Because the grid environment is very dynamic and the services are shared among many users, it is impossible to optimize the workflow from the point of view of execution ahead of time. In fact, one may want to make decisions about the execution locations and the access to a particular data set as late as possible. In this paper, we propose a method of using Contract Net Protocol(CNP) to implement service-oriented workflow mapping in ShanghaiGrid workflow management system(SHGWMS). Three types of workflow in SHGWMS are denoted as Abstract workflow(AW), Concrete workflow(CW) and Executable workflow(EW). Belief-Desire-Intention(BDI) agent technology in SHGWMS helps the system meet challenges from the grid context. CNP provides a very proper negotiation model for agents. The problem of workflow mapping has been transferred to the problem of multi-agent negotiation with the help of CNP model in SHGWMS. We also propose AW2CW mapping algorithm and CW2EW mapping algorithm to accomplish service-oriented workflow mapping.

System and method for controlling distributed power source

Abstract: PROBLEM TO BE SOLVED: To perform optimized high-speed operation by reducing processing time and communication load in a power system with a distributed power source installed therein. SOLUTION: The control system having a switch agent 1 disposed at a section switch within a section separated by the section switch SW1 of the power system as an initiator, a generator and load within the section and agents 2A to 2E disposed at a downstream side switch as a responder, uses a contract net protocol between the agents for power demand/supply contract to control the distributed power source within the section and demand/supply control within the downstream section. Besides, the contract net protocol using the switch agent disposed at an interconnecting point switch as the initiator is used in a unit micro grid in a micro grid to control the demand/supply balance in the section micro grid and downstream micro grid. COPYRIGHT: (C)2009,JPO&INPIT

Job shop dynamic scheduling model based on multi-agent

Abstract: The characteristics of static and dynamic job shop scheduling are discussed. And also analyzes the concept and action of multi-agent system. Bring forward and built a job shop scheduling model based on multi-agent in order to accommodate the changes created in the production process. The job shop production scheduling model and dynamic scheduling model are presented In the model, the entities in the job shop are abstracted as manager agent, task agent and resource agent with multi-agent technology. According to contract net protocol (CNP), agents cooperate with each other through contract net and the process of inviting public bidding makes for completing the production order and dynamic scheduling.

Integration between process planning and scheduling using feature-based time-extended negotiation protocols in a multiagent system

Abstract: This paper describes the adaptation of process plan with alternatives, through an operation-based time extended negotiation protocol for decision-making about real-time routing of job orders of parts composed of machining operations in a job shop environment. The protocol is modified from the contract net protocol to cater for the multiple tasks and many-to-many negotiations. The grouping of the machining operations enables reduction of setup times, resulting from the reduction of machines changes. The time-extended negotiation period allows the visualisation of all the times involved in the manufacture of each part, including those times that are not considered in systems of this nature, such as the negotiation times among agents. Extensive experiments have been conducted, and the performance measures, including routings, makespan and flow time, are compared with those obtained by the following approaches: traditional hierarchical approach, a cooperative coevolutionary algorithm and the search technique based on a coevolutionary algorithm.

Using a Contract Net to Dynamically Configure Sensor Webs

Abstract: We describe how we developed a multi-agent system to represent a collection of sensors that are dynamically combined into a Sensor Web. The sensors use a combination of a Matchmaker architecture together with the Contract Net protocol to enable the reasoned, task-based creation of a dynamic Sensor Web that adapts to the data sensed and to the requirements generated by the agent sensors. We tested our system using EO-1 instruments, and showed how Sensor Web instrument coalitions can be generated based on sensing and processing needs.

HNG: A Robust Architecture for Mobile Robots Systems

Abstract: Researchers in robotics agree that control architectures must be reactive, modular, standardized, reliable, and should allow the use of multiple functions In the last few years, the open challenges organized by the DARPA have shown that robustness can be obtained and that real autonomous systems can be built We conducted an analysis of several control architectures, and especially of those who had good performances in terms of reliability The purpose of this analysis was to select the best mechanisms in the available architectures and to build an architecture that would allow us to proceed to benchmarking and prototyping for perception, planning and control algorithms on real systems in difficult environments As a result, the Hybrid and Network-based Generic architecture HNG uses multiple processes, publish/subscribe communication mechanisms, and its control is based on contract net mechanisms Our preliminary tests show the potential of this approach

Resource Selection Strategies for a CNP-Based Resource Management Model

Abstract: In this paper, we propose a resource management model that extends the contract net protocol by integrating the advantages of the matchmaking technique. Our model addresses the issues of matchmaker overload and the lack of up-to-date resource state information suffered by the original matchmaking model. It also enables resource requesters to obtain a list of qualified resources with which they can narrow down the selection of resources and reduce the number of ineffective communication messages. In addition, we present five strategies to facilitate resource selection on our model from the perspective of turnaround time and reporton experiments to evaluate their performance. The experiment results show that, in the presence of resource contention, the probabilistic strategies outperform random and the deterministic ones, and the performance of the presented strategies executed on our model is superior to their performance on the original matchmaking model.

Controling Contract Net Protocol by Local Observation for Large-Scale Multi-Agent Systems

Abstract: We describe a new adaptive manager-side control policy for the contract net protocol that uses the capabilities of all agents in a massively multi-agent system (MMAS). Recent advances in Internet services, pervasive computing, and grid computing require sophisticated MAS technologies to effectively use the large amount of invested computing resources. To improve overall performance, tasks must be allocated to appropriate agents, and from this viewpoint, a number of negotiation protocols were proposed in the MAS context. Most assume a small-scale, unbusy environment, however. We previously reported the possibility that, using contract net protocol (CNP), the overall efficiency improved by an adequate control of degree of fluctuation in the awarding phase, when the MMAS is in specific states. In this paper, we propose the method to estimate these specific states from the bid values, which have hitherto not been used effectively. Then the new manager-side policy flexibly and autonomously introduces some degree of fluctuation responsive to the estimated states. We also demonstrate that our proposed CNP policy provides considerably better performance than naive CNP and CNP with inflexible policies, even though our policy does not use global information.

Research on the Cooperation of the Multi-agent Based on Extended Contract Net

Abstract: Analyze the shortcoming and limitation in traditional contract net method,we provide a new improved and extended contract net method.Based on the improved contract net method,we study the multi agent cooperation.The method improves the efficiency of the system and the quality of the user task completed by introducing evaluated parameters and expanding the statements of tenderee and bidder.

Multi-Agent Interaction and Cooperation Simulation Using Swarm of Inter-basin Water Transfer

Abstract: The complexity and adaptation in the process of water resource configuration and dispatch management of inter-basin water transfer,characterized by interaction-coordination-adaptability between the agents aggregation of water suppliers and the agents aggregation of water demanders,between the agents and the environments were expounded and analyzed Introducing the contract net protocol,an improved contract protocol and a series of interactive and coordinated behavior rules about tasks and roles distribution,commitment implementation and contract net protocol auto condition machine and algorithm were designed A multi-agent simulation model was given based on contract net protocol of inter-basin water transfer Differing from traditional system kinetic water resource system configuration and dispatch management simulation transfer methods,the complex and adaptive system were adopted as basic system simulation technology and a simulating experiment system on swarm platform was built The results validate the rationality of the research

Collaborative plan exchange: significant reinforcement for contract net based distributed manufacturing systems

Abstract: Contract net protocol had been popularly employed in distributed manufacturing systems. However, it provides almost no guarantee of robustness and optimization of performance. In this paper a method called collaborative plan exchange (CPE) is brought forward as reinforcement for contract net protocol. CPE adds an information exchange process among resource agents to let them get up-to-the-minute information, arrange coherent action, fulfil manufacturing constraints and collaboratively complete tasks. When a disturbance occurs, CPE can inform influenced agents and form new coherent work scheme. Theoretical analysis and experiments indicate that system robustness and performance are improved significantly.

Negotiation Process for Multi-Agent DSS for Manufacturing System

Abstract: Agents and multi-agent systems constitute nowadays a very active field of research. This field is very multidisciplinary since it is sustained by Artificial Intelligence, Distributed Systems, Software Engineering, etc. In most agent applications, the autonomous components need to interact. They need to communicate in order to solve differences of opinion and conflicts of interest. They also need to work together or simply inform each other. It is however important to note that a lot of existing works do not take into account the agents' preferences. In addition, individual decisions in the multi-agent domain are rarely sufficient for producing optimal plans which satisfy all the goals. Therefore, agents need to cooperate to generate the best multi-agent plan through sharing tentative solutions, exchanging sub goals, or having other agents' goals to satisfy. In this paper, we propose a new negotiation mechanism independent of the domain properties in order to handle real-time goals. The mechanism is based on the well-known Contract net Protocol. Integrated Station of Production agents will be equipped with a sufficient behavior to carry out practical operations and simultaneously react to the complex problems caused by the dynamic scheduling in real situations. These agents express their preferences by using ELECTRE III method in order to solve differences. The approach is tested through simple scenarios.

Research on hybrid-genetic algorithm for MAS based job-shop dynamic scheduling

Abstract: Aimed at the job-shop dynamic scheduling for agile manufacturing, genetic algorithms and heuristic rules are combined; a job-shop dynamic scheduling model based on multi-agent and the hybrid-genetic algorithm is proposed. The allocation of the tasks and coordination have been solved by multi-agent consultations based on contract net protocol, then the tasks have been rescheduled by hybrid-genetic algorithm in order to achieve global optimization. Finally, the effectiveness of this method is confirmed by simulation.

A novel contract net negotiation model based on trust mechanism

Abstract: Traditional contract net protocols can simply and flexibly solve the negotiation problem of multi-agent system (MAS). But they canpsilat work very well within the large scale system environment and is ineffective to solve the multi-issue negotiation problem. This paper investigates the reputation contract net protocol (RCNP) and proposes a novel contract net negotiation model based on RCNP. The model synthesizes the previous trust information and the multi-issue negotiation information which can greatly reduce the computational cost introduced by the unnecessary negotiation processes. In order to demonstrate the advantages of the model, a set of experiments were carried out on the JATLite (Java agent template lite) platform. Experimental results indicate that the proposed model improved the performance of the MAS system and the accuracy of the trust evaluation of the negotiation process.

A Multi-Agent System Frame Model for Dynamic Integration

Abstract: Since low flexibility and non-dynamic problems exit in the process of software system integration, a multi-agent system frame model which introduces the agent techniques into system integration domain is proposed for problem solving. Based on the MAS frame model, independent software units are wrapped to agents, and their integration logic is described by the script language. Through explaining the file, the collaboration of multi-agent is under control. Dialogue expansion contract net protocol is used for the cooperation when agent cannot solve problems by itself. In order to achieve the aim of flexible and dynamic integration, new wrapped agents can be added into MAS dynamically and the edited script can be explained by the parser. Finally, the agent-based system integration tools is built upon this frame model, and an application of this model about the border and coast defense system is presented, which verifies the rationality, feasibility and efficiency.

Research of Contract Net Model Based on Cost Timed Petri Net

Abstract: In agent-mediated electronic markets,the negotiation has been used as a mechanism to solve the task distribution,coordination and conflict in virtual enterprises. An agent may delegate part of the assigned tasks to others to achieve the business objectives via establishment of contracts. Electronic contracting relies on an effective model to automate the negotiation processes and analyze the feasibility of the resulting contracts. Firstly,Cost Time Petri Net (CTPN) associates a price with a place,and the semantics for price time Petri net are given. Then the Cost Timed Petri Net is proposed to model the contract net protocol. In the contract net framework,the cooperation processes are verified based on CTPN model. The objectives are to propose a CTPN to model the negotiation processes in contract manufacturing,analyze the feasibility of the contracts and optimize contract awarding based on the proposed model.

A Contract Net Model Based on Agent Active Perception

Abstract: Introducing agent techniques into the process of system integration will solve the problem about flexible dynamic system integration. The contract net protocol (CNP) has been applied to the negotiation in multi-agent system. On the basis of the research on traditional CNP, by improving its ability to deal with dynamic environment, this paper presents a contract net model based on agent active perception (CNMAAP) to improve the efficiency of negotiation. With the introduction of a perception coefficient and a parameter for the degree of credibility to CNMAAP, the paper puts forward the tendering strategy for contract manager and the bidding strategy for contract tender, after which an analysis of the efficiency of CNMAAP is made. Finally, CNMAAP is applied to the agent-based system integration tool, and has been tested with the border and coast defense simulation system. The result demonstrates that, compared with traditional CNP, CNMAAP can effectively reduce the negotiation cost with assured quality.

Method of using BDI agents to implement service-oriented workflow mapping in AGWMS

Abstract: Workflow management is one of the most important parts of ShanghaiGrid, which has a complex service-oriented infrastructure. Because grid environment is very dynamic and services in it are shared among many users, it is impossible to optimise grid workflow from the point of view of execution ahead of time. In fact, one may want to make decisions about the execution locations and the access to a particular data set as late as possible, which is the main objective of grid workflow mapping. In this paper, three types of workflow are denoted as abstract workflow (AW), concrete workflow (CW) and executable workflow (EW). We propose a method of using Belief-desire-intention (BDI) agents to implement service-oriented workflow mapping in the agent-based grid workflow management system (AGWMS) of ShanghaiGrid. BDI agent technology helps the system meet challenges from the grid context. Contract net protocol (CNP) provides a very proper negotiation model for these agents. The problem of workflow mapping has been transferred to the problem of multi-agent negotiation with the help of CNP model in AGWMS. AW2CW and CW2EW mapping algorithms are also given to accomplish service-oriented workflow mapping.