Equilibrium in Scoring Auctions

This paper studies multi-attribute auctions in which a buyer seeks to procure a complex good and evaluate offers using a quasi-linear scoring rule. Suppliers have private information about their costs, which is summarized by a multi-dimensional type. The scoring rule reduces the multidimensional bids submitted by each supplier to a single dimension, the score, which is used for deciding on the allocation and the resulting contractual obligation. We exploit this idea and obtain two kinds of results. First, we characterize the set of equilibria in quasi-linear scoring auctions with multi-dimensional types. In particular, we show that there exists a mapping between the class of equilibria in these scoring auctions and those in standard single object IPV auctions. Second, we prove a new expected utility equivalence theorem for quasi-linear scoring auctions.Auctions, Procurement

Systematic methods for the computation of the directional fields and singular points of fingerprints

The first subject of the paper is the estimation of a high resolution directional field of fingerprints. Traditional methods are discussed and a method, based on principal component analysis, is proposed. The method not only computes the direction in any pixel location, but its coherence as well. It is proven that this method provides exactly the same results as the "averaged square-gradient method" that is known from literature. Undoubtedly, the existence of a completely different equivalent solution increases the insight into the problem's nature. The second subject of the paper is singular point detection. A very efficient algorithm is proposed that extracts singular points from the high-resolution directional field. The algorithm is based on the Poincare index and provides a consistent binary decision that is not based on postprocessing steps like applying a threshold on a continuous resemblance measure for singular points. Furthermore, a method is presented to estimate the orientation of the extracted singular points. The accuracy of the methods is illustrated by experiments on a live-scanned fingerprint databas

Likelihood-Ratio-Based Biometric Verification

The paper presents results on optimal similarity measures for biometric verification based on fixed-length feature vectors. First, we show that the verification of a single user is equivalent to the detection problem, which implies that, for single-user verification, the likelihood ratio is optimal. Second, we show that, under some general conditions, decisions based on posterior probabilities and likelihood ratios are equivalent and result in the same receiver operating curve. However, in a multi-user situation, these two methods lead to different average error rates. As a third result, we prove theoretically that, for multi-user verification, the use of the likelihood ratio is optimal in terms of average error rates. The superiority of this method is illustrated by experiments in fingerprint verification. It is shown that error rates below 10/sup -3/ can be achieved when using multiple fingerprints for template construction

A Multi-Scale Approach to Directional Field Estimation

This paper proposes a robust method for directional field estimation from fingerprint images that combines estimates at multiple scales. The method is able to provide accurate estimates in scratchy regions, while at the same time maintaining correct estimates around singular points. Compared to other methods, the penalty for detecting false singular points is much smaller, because this does not deteriorate the directional field estimate

Diagnosing Foreclosure Due to Exclusive Dealing

Exclusive dealing arrangements, in which a distributor contracts to work exclusively with a single manufacturer, can be efficiency enhancing or they can be an anticompetitive means to foreclose markets. This paper evaluates the effect of exclusive distribution arrangements on competition in the Chicago beer market in 1994. A diagnostic test is provided to judge whether exclusive arrangements between brewers and their distributors lead to foreclosure. To implement this test I estimate a model of consumer demand and firm behavior that incorporates industry details and allows for distribution through exclusive and shared channels. The test indicates that foreclosure effects are not present in this market, suggesting that the most likely effect of intervention would be to reduce social welfare