Negotiation as a Metaphor for Distributed Problem Solving

Abstract We describe the concept of distributed problem solving and define it as the cooperative solution of problems by a decentralized and loosely coupled collection of problem solvers. This approach to problem solving offers the promise of increased performance and provides a useful medium for exploring and developing new problem-solving techniques. We present a framework called the contract net that specifies communication and control in a distributed problem solver. Task distribution is viewed as an interactive process, a discussion carried on between a node with a task to be executed and a group of nodes that may be able to execute the task. We describe the kinds of information that must be passed between nodes during the discussion in order to obtain effective problem-solving behavior. This discussion is the origin of the negotiation metaphor: Task distribution is viewed as a form of contract negotiation. We emphasize that protocols for distributed problem solving should help determine the content of the information transmitted, rather than simply provide a means of sending bits from one node to another. The use of the contract net framework is demonstrated in the solution of a simulated problem in area surveillance, of the sort encountered in ship or air traffic control. We discuss the mode of operation of a distributed sensing system, a network of nodes extending throughout a relatively large geographic area, whose primary aim is the formation of a dynamic map of traffic in the area. From the results of this preliminary study we abstract features of the framework applicable to problem solving in general, examining in particular transfer of control. Comparisons with planner, conniver, hearsay-ii , and pup 6 are used to demonstrate that negotiation—the two-way transfer of information—is a natural extension to the transfer of control mechanisms used in earlier problem-solving systems.

[1]  David L. Waltz,et al.  Understanding Line drawings of Scenes with Shadows , 1975 .

[2]  Donald A. Waterman,et al.  Pattern-Directed Inference Systems , 1981, IEEE Transactions on Pattern Analysis and Machine Intelligence.

[3]  Stephen R. Kimbleton,et al.  Computer Communication Networks: Approaches, Objectives, and Performance Considerations , 1975, CSUR.

[4]  Victor R. Lesser,et al.  The Hearsay-II Speech-Understanding System: Integrating Knowledge to Resolve Uncertainty , 1980, CSUR.

[5]  Edward A. Feigenbaum,et al.  Rule-based understanding of signals , 1977, SGAR.

[6]  Jay R. Galbraith.  Organization Design: An Information Processing View , 1974 .

[7]  Edward K. Bowdon,et al.  Cost effective priority assignment in network computers , 1972, AFIPS '72 (Fall, part II).

[8]  L. G. Roberts,et al.  Computer report III: Data by the packet: Because computing costs are now so low, an unusual new concept of data communications is feasible , 1974, IEEE Spectrum.

[9]  Randall Davis,et al.  Meta-Rules: Reasoning about Control , 1980, Artif. Intell..

[10]  Robert E. Kahn,et al.  The organization of computer resources into a packet radio network , 1899, AFIPS '75.

[11]  Barbara Liskov,et al.  DISTRIBUTED COMPUTER SYSTEMS: STRUCTURE AND SEMANTICS , 1979 .

[12]  Reid G. Smith,et al.  The Contract Net Protocol: High-Level Communication and Control in a Distributed Problem Solver , 1980, IEEE Transactions on Computers.

[13]  Carl Hewitt,et al.  Viewing Control Structures as Patterns of Passing Messages , 1977, Artif. Intell..

[14]  Randall Davis,et al.  Frameworks for Cooperation in Distributed Problem Solving , 1988, IEEE Transactions on Systems, Man, and Cybernetics.

[15]  Victor R. Lesser,et al.  Functionally Accurate, Cooperative Distributed Systems , 1988, IEEE Transactions on Systems, Man, and Cybernetics.

[16]  Victor R. Lesser,et al.  Distributed Interpretation: A Model and Experiment , 1980, IEEE Transactions on Computers.

[17]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[18]  Edward A. Feigenbaum,et al.  RULE-BASED UNDERSTANDING OF SIGNALS1 , 1978 .

[19]  Henry Hamburger,et al.  N‐person Prisoner's Dilemma† , 1973 .

[20]  Carl Hewitt,et al.  Description and Theoretical Analysis (Using Schemata) of Planner: A Language for Proving Theorems and Manipulating Models in a Robot , 1972 .

[21]  Randall Davis,et al.  An overview of production systems , 1975 .

[22]  Jean-Loup Baer,et al.  A Survey of Some Theoretical Aspects of Multiprocessing , 1973, CSUR.

[23]  Robert E. Kahn,et al.  Resource-sharing computer communications networks , 1972 .

[24]  Reid G. Smith,et al.  A Framework for Distributed Problem Solving , 1979, IJCAI.

[25]  Earl D. Sacerdoti,et al.  QLISP - A language for the interactive development of complex systems , 1899 .

[26]  R. G. Smith,et al.  Applications of the Contract Net Framework: Distributed Sensing, , 1978 .

[27]  Cecilia Ruth D'Oliveira.  An Analysis of Computer Decentralization , 1977 .

[28]  Robert N. Noyce.  From Relays to MPU's , 1976, Computer.

[29]  Douglas B. Lenat,et al.  BEINGS: Knowledge as Interacting Experts , 1975, IJCAI.