Browsing by Author "Tsvetovat, Maksim"

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    Evaluating Risk: Flexibility and Feasibility in Multi-Agent Contracting
    (1999-01-09) Sundareswara, Rashmi; Tsvetovat, Maksim; Collins, John; Gini, Maria; van Tonder, Joshua; Mobasher, Bamshad
    In an automated contracting environment, where a "customer" agent must negotiate with other self-interested "supplier" agents in order to execute its plans, there is a trade-off between giving the suppliers sufficient flexibility to incorporate the requirements of the customer's call-for-bids into their own resource schedules, and ensuring the customer that any bids received can be composed into a feasible plan. In this paper, we introduce a bid evaluation process that incorporates cost, task coverage, temporal feasibility, and risk estimation. Using this evaluation process, we provide an empirical study of the trade-offs between flexibility, plan feasibility, and cost in the context of our MAGNET multi-agent contracting market infrastructure. Our experimental results demonstrate that the advantage of increasing supplier flexibilty is dependent on the number of available suppliers. In other words, if the number of suppliers is small, the risk of plan nfeasibility outweighs the advantage of added flexibility. On the other hand, if the numer of suppliers is large, the more flexibile plan specifications result in lower-risk plans.
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    Multi-Agent Contracting for Supply-Chain Management
    (2000-02-10) Collins, John; Sundareswara, Rashmi; Tsvetovat, Maksim; Gini, Maria; Mobasher, Bamshad
    We present a system for multi-agent contract negotiation, implemented as a generalized market architecture called MAGNET. MAGNET provides support for a variety of types of transactions, from simple buying and selling of goods and services to complex multi-agent contract negotiations. In the latter case, MAGNET is designed to negotiate contracts based on temporal and precedence constraints, and includes facilities for dealing with time-based contingencies. The market operates as an explicit intermediary in the negotiation process, which helps in controlling fraud and discouraging counterspeculation.We introduce a multi-criterion, anytime bid evaluation strategy that incorporates cost, task coverage, temporal feasibility, and risk estimation into a simulated annealing framework. We report on an experimental evaluation using a set of increasingly informed search heuristics within simulated annealing. The results show that excess focus on improvement leads to faster improvement early on, at the cost of a lower likelihood of finding a solution that satisfies all the constraints.