On Constraint-Based Reasoning in e-Negotiation Agents

Negotiation typically involves a number of parties with different criteria, constraints and preferences that determine the individual areas of interest, i.e. the range and order of the preferred solutions of each party. The parties usually have a limited common knowledge of each other's areas of interest. Therefore a range of possible agreements, i.e. the common area of interest is typically not known to the parties a priori. In order to find a mutual agreement the parties explore possible agreements by the process of exchanging information in the form of offers. During the negotiation process the range of possible offers of each party changes according to the current information available. As negotiation progresses and more information become available the ranges reduce until an agreement can be found or the parties withdraw from negotiation. This interpretation allows one to consider the negotiation problem as a constraint satisfaction problem and the negotiation process as constraintbased reasoning. This paper presents some aspects of that interpretation. In particular it outlines the constraint-based representation and constraint propagation mechanisms used in an experimental system of e-Negotiation Agents (eNAs). The eNAs can autonomously negotiate the multi-issue terms of transactions in an e-commerce environment tested with the used car trading problem.