Showing papers on "Contract Net Protocol published in 2000"

Agent Theory for Team Formation by Dialogue

Abstract: The process of cooperative problem solving can be divided into four stages. First, finding potential team members, then forming a team followed by constructing a plan for that team. Finally, the plan is executed by the team. Traditionally, protocols like the Contract Net protocol are used for performing the first two stages of the process. In an open environment however, there can be discussion among the agents in order to form a team that can achieve the collective intention of solving the problem. For these cases fixed protocols like contract net do not suffice. In this paper we present a theory for agents that are able to discuss the team formation and subsequently work as a team member until the collective goal has been fulfilled.We also present a solution, using structured dialogues, with an emphasis on persuasion, that can be shown to lead to the required team formation. The dialogues are described formally using modal logics and speech acts.

A comparison of coordinated planning methods for cooperating rovers

Abstract: This paper describes and evaluates three methods for coordinating multiple agents. These agents interact in two ways. First, they are able to work together to achieve a common pool of goals which would require greater time to achieve by any one of the agents operating independently. Second, the agents share resources that are required by the actions needed to accomplish the goals. The first coordination method described is a centralized scheme in which all of the coordination is done at a central location and the agents have no autonomy at the planning level. The second method performs goal allocation using a centralized heuristic planner and (distributed) planners for the individual agents perform detailed planning. The third method uses a contract net protocol to allocate goals and then (distributed) planners for the individual agents perform detailed planning. We compare these approaches and empirically evaluate them using a geological science scenario in which multiple rovers are used to sample spectra of rocks on Mars.

A Task-Swap Negotiation Protocol Based on the Contract Net Paradigm

Abstract: In this paper we propose a market-like negotiation protocol which extends the wellknown Contract Net Protocol to cope with domains where task swap is the only possible type of contract. The agents we consider are heterogeneous and self-interested. The absence of an explicit support for utility transfer determines interesting implications on efficiency and stability; in particular, we propose different design alternatives induced by different compositions of the announcement and the bid, and discusses the strategies supported. Task swapping is more feasible than task selling for many realistic applications; symbolic path planning in autonomous robotic agents is the application on which we focus the description of our approach.

Time-bound negotiation framework for electronic commerce agents

Abstract: For efficient and informative coordination of agents especially in electronic commerce environment, a time-bound agent negotiation framework is proposed utilizing a time-based commitment scheme. By attaching commitment duration to agent messages, the traditional contract net protocol is extended to a time-bound negotiation framework (TBNF). The proposed negotiation framework has a new message type which allows for parties to agree upon the extension of a commitment duration, and a novel commitment concept in the form of negative commitment. The semantics of the messages with the commitment duration are interpreted, and then the three typical negotiation protocols are formally defined and compared — nothing-guaranteed protocol, acceptance-guaranteed protocol , and finite-time guarantee protocol — which can be incorporated into TBNF. The TBNF should provide a background for efficient and effective electronic commerce negotiation while accommodating each agent's adaptive negotiation strategy.

An exception-handling architecture for open electronic marketplaces of contract net software agents

Abstract: Software agent marketplaces require the development of new architectures, which are capable of coping with unreliable computational and network infrastructures, limited trust among independently developed agents and the possibility of systemic failures. In analogy with human societies, agent marketplaces will benefit from the introduction of appropriate electronic exception handling institutions, whose role will be to help guarantee efficiency and fairness in the face of these challenges. This paper presents a research methodology for designing and evaluating such electronic institutions. It also describes how the methodology has been applied in order to design and evaluate an exception handling architecture for robust software agent marketplaces based on the contract net protocol.

Multi-agent architecture for distributed monitoring in flexible manufacturing systems (FMS)

Abstract: This paper describes an intelligent distributed monitoring architecture for flexible manufacturing systems (FMS) based on the multi-agent paradigm. The proposed approach models the FMS by a society of cognitive agents, which monitor a set of heterogeneous resources. These agents have sufficient knowledge for the decision-making and they co-operate together in order to achieve the FMS monitoring functions. The originality of this approach resides in the total distribution of the monitoring functions over the agents and the co-operation of these agents by the contract net protocol for the real-time supervision. These characteristics improve flexibility, extensibility, real-time running, autonomy, fast reaction to faults, and development cost. Experimental results developed in simulation show the feasibility and the potentialities of the proposed multi-agent architecture for distributed monitoring where concepts such us flexibility, co-ordination, reactivity and integration are involved.

Dialogue in Team Formation

Abstract: The process of cooperative problem solving can be divided into four stages. First, finding potential team members, then forming a team followed by constructing a plan for that team. Finally, the plan is executed by the team. Traditionally, very simple protocols like the Contract Net protocol are used for performing the first two stages of the process. And often the team is already taken for granted. In an open environment (like in e.g. electronic commerce) however, there can be discussion among the agents in order to form a team that can achieve the collective goal of solving the problem. For these cases fixed protocols like contract net do not suffice. In this paper we present an alternative solution, using structured dialogues that can be shown to lead to the required team formation. The dialogues are described formally (using some modal logics), thus making it possible to actually prove that a certain dialogue has a specific outcome.

Market-based approach for multi-team robot cooperation

Abstract: The scalability of market-based approaches in multi-robot system coordination enables an assigned task to be decomposed into subcomponents achievable by individuals or subteams within the team. However, in some potential multi-robot system applications, particularly search and rescue operations, this can involve deployment of multiple teams of robots from different parties to work side by side. Each team of robots is independently managed by its operator. A loose collaboration among teams of robots is needed to increase the efficiency of a task completion. This work presents a variant architecture of multi-robot systems using Contract Net Protocol to address the coordination among multiple teams of robots. The system is named a multi-team robot system. It places emphasis on a team's data security in communication where each team operates on a respective communication network while maintaining their collaboration. The method of task coordination is explained in detail and verified on a physical mobile robot platform.

Spatio-Temporal Clustering of Tasks for Swap-Based Negotiation Protocols in Multi-Agent Systems

Abstract: Path planning in robotic agents consists in determining, on a network of places and routes modeling the environment, a sequence of resources to be visited in order to carry out a set of tasks. In multi-agent systems, agents may cooperate to decrease the task execution costs; the Contract Net Protocol is an approach to negotiation of tasks based on the announcement-bid-award mechanism. If the agents do not own money, they can decrease their costs only by swapping tasks with other agents; unfortunately, swapping only single tasks may trap negotiation in local minima of the cost. In this paper we show how the utility of negotiations can be increased by allowing tasks to be swapped in non-disjoint clusters. Clustering of tasks is carried out, in a fuzzy fashion, according to two orthogonal dimensions which consider, respectively, the spatial disposition of the resources within the environment and the temporal progression of their time windows; the approach is scalable to support other dimensions as well.

A Genetic Algorithm-based Approach to Holon Virtual Clustering

Abstract: This paper focuses on the dynamic re-configuration and task optimization of holonic manufacturing systems (HMS). The concept of dynamic virtual clustering is extended to the control process of a holarchy or holonic organization. A task-oriented clustering mechanism and a corresponding optimization algorithm are presented as an efficient approach to the holonic control in the HMS domain. The mediator-based dynamic virtual clustering mechanism is presented firstly. Then a negotiation strategy based on the Contract Net protocol is proposed for cooperative action among holons. Finally, a genetic algorithm-based optimization algorithm for task allocation is described to support the optimum organization of a holarchy. This approach is illustrated through an example.

Agent architecture and theory for team formation by dialogue

Abstract: The process of cooperative problem solving can be divided into four stages First, finding potential team members, then forming a team followed by constructing a plan for that team Finally, the plan is executed by the team Traditionally, protocols like the Contract Net protocol are used for performing the first two stages of the process In an open environment however, there can be discussion among the agents in order to form a team that can achieve the collective intention of solving the problem For these cases fixed protocols like contract net do not suffice In this paper we present an architecture for agents that are able to discuss the team formation and subsequently work as a team member until the collective goal has been fulfilled We also present a solution, using structured dialogues, with an emphasis on persuasion, that can be shown to lead to the required team formation The dialogues are described formally using modal logics and speech acts

Dynamic Social Knowledge: A Comparative Evaluation

Abstract: This paper presents a comparative evaluation of the Contract Net Protocol, the Coalition Based on Dependence and the Dynamic Social Knowledge multi-agent systems cooperation strategies. This evaluation focuses on the number of exchanged messages in the cooperation process.

Three Coordinated Planning Methods for Cooperating Rovers

Abstract: paper describes and evaluates three methods for coordinating multiple agents. These agents interact in two ways. First, they are able to work together to achieve a common pool of goals which would require greater time to achieve by any one of the agents operating independently. Second, the agents share resources that are required by the actions needed to accomplish the goals. The first coordination method described is a centralized scheme in which all of the coordination is done at a central location and the agents have no autonomy at the planning level. The second method performs goal allocation using a centralized heuristic planner and (distributed) planners for the individual agents perform detailed planning. The third method uses a contract net protocol to allocate goals and then (distributed) planners for the individual agents perform detailed planning. We compare these approaches and empirically evaluate them using a geological science scenario in which multiple rovers are used to sample spectra of rocks on Mars

Kqml based contract net protocol model and realization

Abstract: The organization and the properties of a Multi Agent System (MAS) which is based on KQML speaking are firstly analysed in this paper. Then, we propose a MAS model which is based on Contract Net Protocol (CNP) , and an Agents Communication Model which combines with KQML and CORBA is also provided. Lastly, via analysing the formal expression of KQML in a simple application of a scheduling system, we confirm the feasibility of these CNP models.

Use contract switching method and communication provider server

Abstract: PROBLEM TO BE SOLVED: To ease the burden of a user at the subscription by easily changing a pre-paid contract to a post-paid contract, and to reduce the arrears of a communication fee without limiting the type of devices when making a pre-paid contract. SOLUTION: A provider generates provisional edition customer information based on the user's subscription application (S101), and registers it in a data base 55 (S102), and registers it in a pre-paid management system. The pre-paid management system sets a network for pre-paid sue for the customer (S103). Thus, the user can use a service under the pre-paid contract. Afterwards, when the user is identified, official edition customer information is registered in a data base 51 (S108), and any service under the pre-paid contract is stopped, and a service under a post-paid contract is started. Also, when the arrears of a communication fee is generated under the post-paid contract, the post-paid contract is automatically changed to the pre-paid contract.

Introducing Swap-Based Negotiations in the Contract Net Protocol

Abstract: When several agents are placed within an environment to carry out tasks, they may cooperate to decrease the execution costs. In particular, a self-interested agent is inclined towards maximizing its own profit and thus is open to cooperation only if it is an advantage for itself. The Contract Net Protocol (CNP) [Smith, 1980] is an approach to negotiation in multi-agent systems, inspired by a market-like model. In the design alternatives proposed in the literature, tasks are always sold for money. In this paper we outline a negotiation protocol which conforms the contract net paradigm to environments where the only possible type of contract is the swapping. The agents we consider are self-interested and bounded rational; they may have different skills and cost evaluation functions, and must carry out different missions. Thus, the utility of a given swap may differ substantially for the different agents. Since no agent owns models of the others, and there is no money to establish a common cost metric, an agent has no means of estimating the utilities for the other agents. This causes the swap-based protocol to be more stable than the sale-based one.