Showing papers on "Contract Net Protocol published in 1996"

Cooperative transportation scheduling : an application domain for dai

Abstract: A multiagent approach to designing the transportation domain is presented The MARS system is described which models cooperative order scheduling within a society of shipping companies We argue why Distributed Artificial Intelligence (DAI) offers suitable tools to deal with the hard problems in this domain We present three important instances for DAI techniques that proved useful in the transportation application: cooperation among the agents, task decomposition and task allocation, and decentralised planning An extension of the contract net protocol for task decomposition and task allocation is presented; we show that it can be used to obtain good initial solutions for complex resource allocation problems By introducing global information based upon auction protocols, this initial solution can be improved significantly We demonstrate that the auction mechanism used for schedule optimisation can also be used for implementing dynamic replanning Experimental results are provided evaluating the performance of different scheduling strategies

A holonic approach for task scheduling in manufacturing systems

Abstract: This paper deals with a new architecture and negotiation protocol for the dynamic scheduling of manufacturing systems. The architecture is based on two paradigms: multi-agent systems and holonic systems. The main contribution in the architecture is the existence of holons representing tasks together with holons representing resources. The well known contract net protocol has been adapted to handle temporal constraints and to deal with conflicts. The purpose of this protocol is to dynamically assign operations to the resources of the manufacturing system in order to accomplish the proposed tasks. This protocol involves a renegotiation phase whenever exceptions appear. It also deals with conflict situations, namely with the case of the "indecision problem". The approach we are using assumes that deadlines are the most important constraints to consider, thus the acceptance or refusal of a resource for a specific operation depends on the capability of executing the operation in the specified deadline.

Formalising the contract net as a goal-directed system

Abstract: In response to the problems that have arisen regarding the terminology and concepts of agent-oriented systems, previous work has described a formal framework for understanding agency and autonomy. In this paper we outline the framework and refine it by adding further levels of detail to develop a formal model of the Contract Net Protocol. The model serves to make precise both the operations of nodes in the contract net, and the state of the net at various points during the protocol. In particular, the nature of the dependencies between the nodes in the net is explicated. Finally, we generalise the relationships that can be found in the contract net which are brought out by the formalisation, and introduce more general concepts such as cooperation and engagement.

Reducing Communication Load on Contract Net by Case-Based Reasoning -- Extension with Directed Contract and Forgetting --

Abstract: This paper describes the communication load reduction on the task negotiation with Cont.rart Net Protor~d for multiph: autonomou~ lnobilc robots. Wc have dcvek)pe(l LEMMING. a task negotiation system with low ~xmnmtnication load for nmltiple atttonomolts mobile robots. For controlling multiple robots, Contract Net Protocol(CNP) is useful, but the broadcast of the Task Announcement messages on CNP tends to consnnic lnltdl comnnmicatitm load. In ordcr to overcome this probhun LEMMIN(; learns proper addressees for the Task Announct,nlcnt message.s with Case-Ba.~ed Rcasoning(CBl’t) so as to suppress the broadcast. The learning method is called Addrrssee Learning. In this paper, we extend LEMMING with "dirertcd contract" to r~lucc the communication load more cffectivcly. Moreover. wc extend LEMMING with "forgetting" to restrict the munbex of cases, sillcc it is impossible to have enough memory to keep MI the cases. The efficiency of LEMMI.NG is cvaluated in a silmtlated multi-robot environment to show that these extensions arc effec.tive for LEMMI.~e;.

Analyzing the social behavior of contract net protocol

Abstract: Contract Net Protocol (CNP) assigns subtasks to agents which are involved in multiagent problem solving. Although the logical aspects of the negotiation protocol have been analyzed, the social behavior of protocol dynamics remain unclear.

Addressee Learning and Message Interception for Communication Load Reduction in Multiple Robot Environments

Abstract: This paper describes communication load reduction on task negotiation with Contract Net Protocol for multiple autonomous mobile robots. We have developed Lemming[5, 6, 7], a task negotiation system with low communication load for multiple autonomous mobile robots. For controlling multiple robots, Contract Net Protocol(CNP)[10] is useful, but the broadcast of the Task Announcement messages on CNP tends to consume much communication load. In order to overcome this problem Lemming learns proper addressees for the Task Announcement messages with Case-Based Reasoning[3] so as to suppress the broadcast. The learning method is called Addressee Learning. However the learning method causes inefficient task execution. An extension of Lemming with Message Interception which enables the system to execute tasks more efficiently is reported.

Agents breaking away : 7th European Workshop on Modelling Autonomous Agents in a Multi-Agent World, MAAMAW '96, Einhoven, the Netherlands, January 22-25, 1996 : proceedings

Abstract: Ideal and real belief about belief: Some intuitions.- Emotions as commitments operators: A foundation for control structure in multi-agents systems.- A logical and operational model of scalable knowledge- and perception-based agents.- AgentSpeak(L): BDI agents speak out in a logical computable language.- A methodology and modelling technique for systems of BDI agents.- Formalising the Contract Net as a goal-directed system.- A coordination algorithm for Multi-Agent planning.- Modelling approach and tool for designing protocols for automated cooperation in multi-agent systems.- Analyzing the social behavior of Contract Net Protocol.- Effects of different interaction attitudes on a multi-agent system performance.- Bacterial Evolution Algorithm for rapid adaptation.- Distributed interaction with computon.- SIGMA: Application of Multi-Agent Systems to Cartographic Generalization.- A decision-theoretic model for cooperative transportation scheduling.- A real-time agent model in an asynchronous-object environment.- Coalition formation among rational information agents.- Cooperating agents implementing distributed patient management.

An extension of contract net protocol with real time constraints

Abstract: The contract net protocol has developed to specify problem solving communication for nodes in a distributed problem solving. Task distribution is affected by a negotiation process, a discussion carried on between nodes with tasks to be executed and nodes that may be able to execute those tasks. In contract net protocol, once negotiation successes, the task execution is assumed to success. However, in real world, even though a task is awarded to successfully bidding nodes, it may be delayed. Such delay may badly propagate in whole system. Here, we introduce real-time constraints into contract net protocol to manage task execution for avoiding the task's delay, or even though being delayed, the failure cannot propagate to whole system. In this paper, we first present a real-time contract net protocol which is an extension of contract net protocol with real-time constraints for distributed computing. Our proposition extends the basic negotiation protocol to negotiation and controlling execution of task. The controlling process is based on task deadline time we also present an extension of the internode language of contract net protocol specification with real-time constraints