Towards Comprehensive Real-Time Bidder Support in Iterative Combinatorial Auctions (Research Seminar,January 29th, 2004) Gedas Adomavicius University of Minnesota Abstract Many auctions involve selling several distinct items simultaneously, where bidders can bid on the whole or any part of the lot. Such auctions are referred to as combinatorial auctions. Examples of such auctions include truck delivery routes, furniture, and FCC spectrum. Determining winners in such auctions is an NP-complete problem and significant research is being conducted in this area. However, multiple round (iterative) combinatorial auctions present significant challenges in bid formulations as well. Since the combinatorial dynamics in iterative auctions can make a given bid a part of winning and non-winning set of bids without any changes in the bid, bidders are usually not able to evaluate whether they should revise their bid at a given point in time or not. Therefore, in this talk we address various computational problems that are relevant from the bidder's perspective. In particular, we introduce several bid evaluation metrics that can be used by bidders to determine whether any given bid can be a part of the winning allocation and explore their theoretical properties. Based on these metrics, we also develop efficient data structures and algorithms that provide comprehensive information about the current state of the auction at any time, which can help bidders in evaluating their bids and bidding strategies. The performance analysis suggests that the proposed approach is suitable for real-time bidder support.