ELSEVIER European Journal of Operational Research 103 (1997) 389-409 EUROPEAN JOURNAL OF OPERATIONAL RESEARCH Negotiation support systems: A multi-criteria and multi-agent approach Bernard Espinasse *, Guy Picolet, Eugene Chouraqui DIAM-IUSPIM, Uniuersitd Aix-Marseille Ill, Campus Scientifique de Saint J&g~me, 13397 Marseille, Cedex 13, France Abstract This research concerns the development of an Negotiation Support Systems (NSS) based on a multi-criteria conceptual framework of the negotiation and developed according to a multi-agent architecture from Distributed Artificial Intelligence (DAI). A first prototype of such a system, NegoclAD, has already been developed [8], but the weakness of its assistance to the negotiation process have led us to revise the conceptual framework in order to define a more relevant assistance to the negotiation process. This paper presents this new conceptual framework defined in order to develop a new prototype. First, we point out the originality of our multi-criteria and multi-agent approach, the general architecture and the limitations of NegoclAD. Then we present the new multi-criteria conceptual framework mainly based on the definition and the use of projection plans (group Gaia plans) emerging from principal component analysis (PCA) already proposed in a single decision maker context in extension of the Promethee method. In the next part, we develop the possible levels of use of these plans during the negotiation process and the type of assistance provided to the mediator. This assistance is mainly based on the elaboration and the interpretation of group Gaia plans for which we propose a set of interpretation rules and the outline of a method to make use of these rules for a relevant support to the mediator in the management of the negotiation process. Finally, we conclude on the perspectives of our future researches and developments tbr the new generation of our prototype in a multi-agent architecture context. © 1997 Elsevier Science B.V. Keyword~: Negotialion; Decision support systems; Negotiation support systems; Multi-criteria analysis; Multi-agent systems; Distributed artificial intelligence 1. Introduction Negotiation processes are often characterised by conflicts of interest and a non-cooperation, the exis- tence of various sources of information and rules, proper to each negotiator (that one is not willing to • Corresponding author. E-mail: bernard.espinasse@iuspim.u- 3mrs.fr divulge or share), a mutual lack of confidence, a doubt about the sincerity and the good will of the other actors, and finally, exchanges of the 'bargain- ing' type. The concept of Negotiation Support System (NSS) is as recent as that of Group Decision Support System (GDSS) [8]. It has taken such an importance in the scientific community that the title NSS has merged with that of GDSS to make only a single field of research: the GDNSS [6]. Several NSS have already been developed [13]. A NSS permits to join 0377-2217/97/$17.00 © 1997 Elsevier Science B.V. All rights reserved. PII S0377-22 1 7(97)001 27-6