Showing papers on "Contract Net Protocol published in 2001"

Creating collective intention through 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 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

Dynamic manufacturing scheduling using both functional and resource related agents

Abstract: Manufacturing scheduling is a difficult problem, particularly when it takes place in an open and dynamic environment. Agent-based technology has recently been used in attempts to resolve this problem. A bidding mechanism based on Contract Net protocol is often proposed as a key solution component. Our approach is to use both functional and physical resource related agents, and combine a bidding mechanism based on Contract Net protocol with a mediation mechanism based on Mediator architecture for realizing dynamic manufacturing scheduling and rescheduling. A machine-centered scheduling mechanism and related concepts and mechanisms are described, and a prototype implementation is presented.

Electronic contracts with primary and sponsored roles

Abstract: Computer-based methods and systems are provided for constructing, deploying, executing and managing the performance of electronic contract based service applications across multiple business entities. In this context, the electronic service contract includes information to be used for configuration and enforcement not just by the primary parties to the contract, but also by other parties referred to herein as sponsored roles in the contract. At least a portion of the contract may be monitored, enforced or managed by at least one of the sponsored roles. In one aspect of the invention, a computer-based electronic business service system includes: (1) a contract builder; (2) a contract deployment component; (3) one or more measurement systems; (4) a violation detection system; and (5) a management system. Generally, the contract builder component provides the mechanism for defining and pricing the contract, checking the validity of the contract and a repository for storing the completed contracts. The deployment system is responsible for configuring the (run-time) system in order to meet one or a set of contracts. The measurement system maintains information on the current system configuration, and run-time information on the metrics that are part of the contract. The violation detection system is responsible for comparing measured parameters against the thresholds defined in the contract and notifying the management system. Upon receipt of a notification, the management system will then issue appropriate actions to correct the problem, as specified in the contract.

Peer to peer transactions in agent-mediated electronic commerce

Abstract: This thesis proposes a new approach to electronic markets that overcomes the shortcomings of existing electronic markets through software agent-driven, peer-to-peer, iterative negotiations. Contemporary electronic markets commonly capture both the customs and shortcomings of traditional practice. Rule-based and bound to traditional models, contemporary electronic markets are overly controlling, segregated, inflexible, weakly automated and fixated on price. Many prior attempts to interpose electronic exchanges in existing markets have failed or encountered resistance from traders. Traders’ resistance is interpreted here as a call for systems that bend to the will of traders while channeling self-interested actions toward healthy market practices. The Atomic Market is both a model for an agent-based, peer-to-peer marketplace, and a working system that shows the model in operation. The Atomic Market architecture defines a decentralized marketplace wholly controlled by traders through a new protocol for distributed negotiation. The demonstration system is a collection of independent software agents that pursue economic exchanges via the Atomic Market methodology. In the Atomic Market, multiple agents resolve their self-interests though cycles of rewriting a “contract” comprised of descriptive, flexible terms tailored to the needs of each trader. The Atomic Market interprets the Contract Net Protocol as a message-passing system for economic negotiations, in which agents conduct broad, parallel searches to discover opportunities and trading partners in an open marketplace.

A bidding decision model in multiagent supply chain planning

Abstract: The multiagent environment for supply chain planning application is based on a framework unifying the internal behaviour of agents and coordination among agents. This system presents a formal view of coordination using Contract Net Protocol (CNP) that relies on the basic loop of agent behaviours: order receiving, order announcement, bid calculation, and order scheduling followed by order execution. Among these, bid calculation is most difficult. It needs to determine the quantity, cost and time in which a new order can be implemented. Fuzzy programming has made progress in mathematics since Bellman and Zadeh (1970) first studied decision-making in a fuzzy mathematics programming. Currently there are many valuable works in this field (Zimmermann 1983, 1985, Tanaka and Asai 1984) and fuzzy programming has become an effective tool to deal with the decision-making problems in fuzzy systems. Similarly, stochastic programming is a useful tool to treat decision-making problems in a stochastic system (Kolbin 1977...

The Evolution of the Contract Net Protocol

Abstract: Contracts are a powerful co-ordination mechanism in distributed systems. The contract net protocol has been applied since about 1980. The CNP distributes tasks to different problem-solving nodes. TRACONET extended CNP with a bidding and awarding decision process based on marginal cost calculations. The CIA(Cooperative Information Agent) framework introduced the notion of obligations, which was broadened by CAS (Contractual Agent Societies) to support the fluid organisation of agent societies. Finally, the TPA framework (Trading Partner Agreement) introduced by IBM, although not agent-based, uses contracts as well, it uses executable contract in particular. We will analyse these four different contract model related researches (CNP, TRACONET, CAS and TPA) to compare their capabilities, background assumptions and limitations. We propose an integrated architecture and discuss the essential requirements still to be met.

On-line real-time monitoring system and method of on-line real-time monitoring business

Abstract: A monitoring contract with regard to software and/or hardware which are installed in a terminal is concluded by an access from the above-mentioned terminal connectable to a network to a home page set up by a partner of the contract such as makers or information buyers and the like. After concluding the monitoring contract, utilization information with regard to the software and/or the hardware designated as objects of the monitoring contract in the users' terminal is automatically transferred from the above-mentioned terminal to a predetermined node of the partner of the monitoring contract via the above-mentioned network in real time during utilization of the above-mentioned software and/or hardware by a control program accompanying with the above-mentioned monitoring contract distributed by the above-mentioned partner of the contract installed and installed in the above-mentioned terminal. And the payment of the fee as a compensation with respect to the above-mentioned user of the terminal for providing the above-mentioned utilization information is performed by the above-mentioned partner of the contract when predetermined conditions with regard to the monitoring are satisfied.

Debugging agent interactions: a case study

Abstract: The Contract Net protocol is a general-purpose protocol for distributed problem solving. Many modern agent infrastructures facilitate the generation of agents supporting Contract Net. We used one such infrastructure to simulate a Contract Net-based approach to job scheduling and found that some jobs failed to get scheduled even though the resources were available. This paper describes two phases of the subsequent debugging effort. The first phase was enhancing the visualization of the agent community to reveal the causes of failed negotiations. The second phase was formalizing the problem using a Temporal Calculus of Communicating Systems (TCCS) and attempting to find a solution. After exploring a number of solutions that would not generalize, we found that switching from one-stage to two-stage commitment sufficed. For coordination problems in general, our case study demonstrates the applicability of rigorous methods and the importance of providing run-time visibility into agents' logic.

A Contract Decommitment Protocol for Automated Negotiation in Time Variant Environments.

Abstract: Negotiation is a fundamental mechanism in distributed multi-agent systems. Since negotiation is a time-spending process, in many scenarios agents have to take into account the passage of time and to react to uncertain events. The possibility to decommit from a contract is considered a powerful technique to manage this aspect. This paper considers interactions among self-interested and autonomous agent, each with their own utility function, and focuses on incomplete information. We define a negotiation model based on asynchronous message passing in which the negotiation doesn’t end when an agreement is reached but when the consequences of the contract have happened – i.e. the action is done. In this model the agent utility functions are time dependent. We present an extension of the contract net protocol that implements the model.

Distributed algorithm for task allocation in multi-agent system based on contract net

Abstract: Coordination and cooperation are two major concerns in multi-agent system (MAS). How can a set of tasks be allocated properly to a group of agents is the key problem for coordination and cooperation. This was dons as. First, the concept of task coalition was defined and the task allocation was transformed into a set-covering problem, Second, the MAS was assumedts conformed to the contract net protocol, a heuristic algorithm for task allocation was proposed based on set-covering theory. Third, the convergence and supremum of the algorithm were proved, and the asymptotic time complexity was analyzed; At last, a simple example was given. With the property of the distributed calculation and quick reduction of the search space, the algorithm is suitable for task distributed problem solving for small and middle scale multi-agent system.

Distributed framework for delivery of medical image processing algorithms

Abstract: The availability of new digital detector technologies and high speed computer processing has led to the development of CAD (computer-aided diagnostic) tools that assist radiologists in detecting and characterizing mammographic lesions. To meet the challenge of developing and implementing algorithms that are computationally intensive, it is desirable to develop reusable components that can execute in a distributed environment. It is well know that the Common Object Request Broker Architecture (CORBA) provides an open solution in distributed computing. We have implemented a hybrid component model consisting of a CORBA server and a Contract Net Protocol (CNP) algorithm for distributing tasks to multiple computers for enhanced processing. Support classes were developed to wrap algorithms developed in C to operate within the distributed framework. CORBA provides communication between agents on different computers and computer platforms and the CNP algorithm is used to select the 'optimal' computer for performing a task. We have evaluated this framework with CAD processing applied to digitized mammograms by transparently scheduling and distributing multiple tasks on three server computers. We achieved a significant reduction in processing times compared to processing on a single computer.