Negotiation and Conflict Resolution in Non-Cooperative Domains

In previous work [Zlotkin and Rosenschein, 1989a], we have developed a negotiation protocol and offered some negotiation strategies that are in equilibrium. This negotiation process can be used only when the “negotiation set” (NS) is not empty. Domains in which the negotiation sets are never empty are called cooperative domains; in general non-cooperative domains, the negotiation set is sometimes empty. In this paper, we present a theoretical negotiation model for rational agents in general noncooper at ive domains. Necessary and sufficient conditions for cooperation are outlined. By redefining the concept of utility, we are able to enlarge the number of situations that have a cooperative solution. An approach is offered for conflict resolution, and it is shown that even in a conflict situation, partial cooperative steps can be taken by interacting agents (that is, agents in fundamental conflict might still agree to cooperate up to a certain point). A Unified Negotiation Protocol is developed that can be used in all cases. It is shown that in certain borderline cooperative situations, a partial cooperative agreement (i.e., one that does not achieve all agents’ goals) might be preferred by all agents, even though there exists a rational agreement that would achieve all their goals. Introduction Definition 2 Plans The subject of negotiation has been of continuing interest in the distributed artificial intelligence (DAI) community [Smith, 1978; Rosenschein and Genesereth, 1985; Durfee, 1988; Malone et al., 1988; Sycara, 1988; Sycara, 1989; Kuwabara and Lesser, 1989; Conry et al., 19881. The operation of cooperating, intelligent autonomous agents would be greatly enhanced if they were able to communicate their respective desires and A one-agent plan to move the world from. state s to state f in ST is a list [ol, 02,. . . , on] of operations from OP such that f = o,(o,-I(. . .01(s) . . .)). A joint plan to move the world from state s to state f in ST is a pair of one-agent plans (PA, PB) and a schedule. A schedule is a partial order over the union of actions in the two one-agent plans. It specifies that some actions cannot be taken until other actions are completed; because it is a partial order, it of course allows *Supported in part by the Leibniz Center for Research in Computer Science. compromise to reach mutually beneficial agreements. The work described in this paper follows the general direction of [Rosenschein and Genesereth, 1985; Zlotkin and Rosenschein, 1989a] in treating negotiation in the spirit of game theory, while altering game theory assumptions that are irrelevant to DAI. Previous work [Zlotkin and Rosenschein, 1989a] discussed inter-agent negotiation protocols and negotiation strategies that were in equilibrium, but could only be used if the s-called “negotiation set” [Harsanyi, 19771 was not empty. Cooperative domains are those in which NS is never empty; in this paper, we present a theoretical negotiation model for general non-cooperative domains (where NS might be empty).