Automated negotiation and coalition formation among self-interested agents are playing an increasingly important role in electronic commerce. Such agents cannot be coordinated by externally imposing their strategies. Instead the interaction protocols have to be designed so that each agent is motivated to follow the strategies that the protocol designer wants it to follow. This paper reviews six component technologies that we have developed for making such interactions less manipulable and more e cient in terms of the computational processes and the outcomes: 1. OCSM-contracts in marginal cost based contracting, 2. leveled commitment contracts, 3. anytime coalition structure generation with worst case guarantees, 4. trading o computation cost against optimization quality within each coalition, 5. distributing search among insincere agents, and 6. unenforced contract execution. Each of these technologies represents a di erent way of battling selfinterest and combinatorial complexity simultaneously. This is a key battle when multiagent systems move into large-scale open settings.

The capability to reallocate items---e.g. tasks, securities, bandwidth slices, Mega Watt hours of electricity, and collectibles---is a key feature in automated negotiation. Especially when agents have preferences over combinations of items, this is highly nontrivial. Marginal cost based reallocation leads to an anytime algorithm where every agent's utility increases monotonically over time. Different contract types head toward different locally optimal task allocations, and contracts from a recently introduced comprehensive contract type, OCSM-contracts, head toward the global optimum. Reaching it can take impractically long, so it is important to trade off solution quality against negotiation time. To construct negotiation protocols that lead to the best achievable allocations in a bounded amount of time, we compared sequences of four contract types: original, cluster, swap, and multiagent contracts. The experiments show that it is profitable to use multiple contract types in the sequ...

decentralised systems, communication protocols © Copyright Hewlett-Packard Company 1998 There are a variety of choices which need to be made when setting up a multi-agent community. In particular, which agents communicate with which, what protocols they use, and what information flows from one to another. Such design choices will affect the efficiency of the community with respect to several parameters – accuracy, speed of solution, and message load. In this paper, we consider one class of problem in which multi-agent systems engage – service provision. Using a simple, abstract, form of this problem, we use a mathematical analysis to show that three different messaging protocols result in varying message loads, depending on certain parameters such as number of agents and frequency of request. If the parameters are fixed, we can conclude that one of these three protocols is better than the others. However, these parameters will usually vary over time, and hence the best of the three protocols will vary. We show that the community can adopt the best protocol if each individual agent makes a local decision based on which protocol will minimise its own message load. Hence, local decisions lead to globally good behaviour. We demonstrate this both mathematically and experimentally. 1.