We study an optimal collusion-proof auction in an environment where subsets of bidders may collude not just on their bids but also on their participation. Despite their ability to collude on participation, informational asymmetry facing the potential colluders can be exploited significantly to weaken their collusive power. The second-best auction — i.e., the optimal auction in a collusion-free ...

In this paper we survey some results concerning balls-intobins-games and the power of two choices. We present a unified and rather elementary analysis for models in the parallel as well as in the sequential setting which is based on witness trees.

The purpose of this review was to examine published research on small-group development done in the last ten years that would constitute an empirical test of Tuckman’s (1965) hypothesis that groups go through these stages of “forming,” “storming,” “norming,” and “performing.” Of the twenty-two studies reviewed, only one set out to directly test this hypothesis, although many of the others could...

The aim of this article was to describe the attention functioning of twenty-two truck drivers and its relationship with amphetamine use. Those drivers who reported using amphetamines in the twelve months previous to the interview had the best performance in a test evaluating sustained attention functioning. Although amphetamine use may initially seem advantageous to the drivers, it may actually...

We prove that under mild regularity assumptions on the initial data the two-phase classical Stefan problem admits a (unique) solution that is analytic in space and time.

This note points out some restrictions imposed by the notion of ratification. This notion is widely used in the mechanism design literature that assumes that each agent has a veto power. We exhibit allocations that are not ratifiable and nevertheless can be implemented through a mechanism that gives veto power to the agents.

Recall. Let π : X → ∆ be a semistable degeneration of K3 surfaces (i.e. a proper, flat, surjective morphism π : X → ∆ whose general fibre Xt = π−1(t) for t ∈ ∆∗ = ∆ − {0} is a smooth K3 surface, such that X is smooth and X0 := π −1(0) is reduced with normal crossings). Then Kulikov [Kul77] [Kul81] and Persson-Pinkham [PP81] show that we can perform birational modifications that affect only the ...

We propose a supervised, two-phase framework to address the problem of paraphrase recognition (PR). Unlike most PR systems that focus on sentence similarity, our framework detects dissimilarities between sentences and makes its paraphrase judgment based on the significance of such dissimilarities. The ability to differentiate significant dissimilarities not only reveals what makes two sentences...

In this paper a new example of quasi–Hermitian variety V in PG(r, q) is provided, where q is an odd power of 2. In higherdimensional spaces, V can be viewed as a generalization of the Buekenhout-Tits unital in the desarguesian projective plane; see [9].

Abstract In this paper, we construct three binary linear codes C(SO−(2, q)), C(O−(2, q)), C(SO−(4, q)), respectively associated with the orthogonal groups SO−(2, q), O−(2, q), SO−(4, q), with q powers of two. Then we obtain recursive formulas for the power moments of Kloosterman and 2-dimensional Kloosterman sums in terms of the frequencies of weights in the codes. This is done via Pless power ...