Planning for Decentralized Control of Multiple Robots Under Uncertainty

We describe a probabilistic framework for synthesizing control policies for general multi-robot systems, given environment and sensor models and a cost function. Decentralized, partially observable Markov decision processes (Dec-POMDPs) are a general model of decision processes where a team of agents must cooperate to optimize some objective (specified by a shared reward or cost function) in the presence of uncertainty, but where communication limitations mean that the agents cannot share their state, so execution must proceed in a decentralized fashion. While Dec-POMDPs are typically intractable to solve for real-world problems, recent research on the use of macro-actions in Dec-POMDPs has significantly increased the size of problem that can be practically solved as a Dec-POMDP. We describe this general model, and show how, in contrast to most existing methods that are specialized to a particular problem class, it can synthesize control policies that use whatever opportunities for coordination are present in the problem, while balancing off uncertainty in outcomes, sensor information, and information about other agents. We use three variations on a warehouse task to show that a single planner of this type can generate cooperative behavior using task allocation, direct communication, and signaling, as appropriate

Improving working relationships for smallholder farmers in formal organic crop supply chains: Evidence from KwaZulu-Natal, South Africa

The 48 members of the Ezemvelo Farmers' Organisation (EFO) in KwaZulu-Natal, South Africa (SA), that are fully-certified as organic farmers were surveyed in October-December 2004 to assess their perceived levels of satisfaction, trust, cooperation and commitment in a formal supply chain producing amadhumbes (a traditional vegetable tuber), potatoes and sweet potatoes for a major SA supermarket group. Empirical recursive models show that a high level of satisfaction in the working relationship results in these farmers trusting the pack-house agent more. High levels of trust, in turn, lead to higher levels of both commitment to, and cooperation in, the supply chain. A simultaneous-equation model showed that EFO members with higher levels of commitment tend to be more cooperative, and that members with higher levels of cooperation tend to be more committed toward the working relationship. These results suggest that strategies to improve the working relationship with the pack-house agent need to promote satisfaction, trust, cooperation and commitment. For example, co-investment in better crop storage facilities at farm-level would promote satisfaction and hence trust. There is also scope for more cooperation in the planning of new organic crop products to grow and market, and to remove some price uncertainty by giving EFO farmers more information about prices that they will be paid by the pack-house in this supply chain.Industrial Organization,

Cooperation and Competition when Bidding for Complex Projects: Centralized and Decentralized Perspectives

To successfully complete a complex project, be it a construction of an airport or of a backbone IT system, agents (companies or individuals) must form a team having required competences and resources. A team can be formed either by the project issuer based on individual agents' offers (centralized formation); or by the agents themselves (decentralized formation) bidding for a project as a consortium---in that case many feasible teams compete for the contract. We investigate rational strategies of the agents (what salary should they ask? with whom should they team up?). We propose concepts to characterize the stability of the winning teams and study their computational complexity

Electric power scheduling: A distributed problem-solving approach

Space Station Freedom's power system, along with the spacecraft's other subsystems, needs to carefully conserve its resources and yet strive to maximize overall Station productivity. Due to Freedom's distributed design, each subsystem must work cooperatively within the Station community. There is a need for a scheduling tool which will preserve this distributed structure, allow each subsystem the latitude to satisfy its own constraints, and preserve individual value systems while maintaining Station-wide integrity. The value-driven free-market economic model is such a tool

Game Theory and Economic Behavior

Until the beginning of 1950s, the economic theory in general, and the microeconomic theory in particular, relied totally on the deterministic character of economic phenomena. Nowadays microeconomic models are built on uncertain elements in a competitive environment that is affected by risk and uncertainty. Two centuries later, traditional microeconomics, also known as derived microeconomics, continues to be based on Adam Smith’s theory. As individuals are interested in participating in commercial transactions, but for these to take place effectively, two essential principles should be observed: the principle of rationality and the principle of pure and perfect competition. The link between Brower’ fixed point theorems on the one hand and John von Neumann’s minimax theorem on the other hand enabled other authors such as McKenzie Arrow and Debreu Uzawa to state and demonstrate simpler but more general theorems than that of Abraham Wald. It was thus supposed that consumer preferences in a pool of possible consumptions are reflexive, transitive and all are comparable. Using game theory as a reference framework to represent the behavior of economic agents, microeconomics strongly renews its scope of investigation. The problem that arises is no longer linked to the study of perfectly competitive markets, but mostly to how agents coordinate their decisions in different strategic configuration circumstances. The use of such concepts as risk, antiselection or coordination limits has opened new scopes to economy in general and to microeconomics in particular.Game Theory, behavior of economic, traditional microeconomics, new microeconomics

Mechanisms for Automated Negotiation in State Oriented Domains

This paper lays part of the groundwork for a domain theory of negotiation, that is, a way of classifying interactions so that it is clear, given a domain, which negotiation mechanisms and strategies are appropriate. We define State Oriented Domains, a general category of interaction. Necessary and sufficient conditions for cooperation are outlined. We use the notion of worth in an altered definition of utility, thus enabling agreements in a wider class of joint-goal reachable situations. 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 (UNP) is developed that can be used in all types of encounters. 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. Finally, we analyze cases where agents have incomplete information on the goals and worth of other agents. First we consider the case where agents' goals are private information, and we analyze what goal declaration strategies the agents might adopt to increase their utility. Then, we consider the situation where the agents' goals (and therefore stand-alone costs) are common knowledge, but the worth they attach to their goals is private information. We introduce two mechanisms, one 'strict', the other 'tolerant', and analyze their affects on the stability and efficiency of negotiation outcomes.Comment: See http://www.jair.org/ for any accompanying file