The degree to which discrimination causes the large racial disparities in the criminal justice system is a long-standing and difficult empirical question. This paper studies a decision in which the influence of race on prosecutors is directly observed: the process of obtaining judicial approval to conduct wiretap surveillance. The Department of Justice requires that federal prosecutors obtain i...

We present new estimates of the effect that obtaining legal immigration status has upon the wages of undocumented workers. In estimating the effect of legalization upon wages, we face a number of econometric challenges. First, through the use of rich panel data, we are able to control for the fact that individuals with higher time invariant unobserved ability, which will raise earnings regardle...

This paper proposes an improved predictor-corrector interior-point algorithm for the linear complementarity problem LCP based on the Mizuno-Todd-Ye algorithm. The modified corrector steps in our algorithm cannot only draw the iteration point back to a narrower neighborhood of the center path but also reduce the duality gap. It implies that the improved algorithm can converge faster than the MTY...

In their work on ‘Coxeter-like complexes’, Babson and Reiner introduced a simplicial complex ∆T associated to each tree T on n nodes, generalizing chessboard complexes and type A Coxeter complexes. They conjectured that ∆T is (n− b−1)-connected when the tree has b leaves. We provide a shelling for the (n − b)skeleton of ∆T , thereby proving this conjecture. In the process, we introduce notions ...

We study complex Coxeter diagrams of some unitary reflection groups. Using solely the combinatorics of diagrams, we give a new proof of the classification of root lattices defined over E = Z[e2πi/3]: there are only four such lattices, namely, the E–lattices whose real forms are A2, D4, E6 and E8. Next, we address the issue of characterizing the diagrams for unitary reflection groups, a question...

These notes were produced in response to a question from John Cannon: what issues are involved in adding facilities to CAYLEY for doing finite geometry? More specifically, what facilities would geometers want? At first sight, the idea of geometry in CAYLEY seems very natural. Groups and geometry have been intimately linked since long before the time of Klein. Many of the groups with which CAYLE...

A full Nesterov-Todd (NT) step infeasible interior-point algorithm is proposed for solving monotone linear complementarity problems over symmetric cones by using Euclidean Jordan algebra. Two types of full NT-steps are used, feasibility steps and centering steps. The algorithm starts from strictly feasible iterates of a perturbed problem, and, using the central path and feasibility steps, finds...

Academics and practitioners optimize portfolios using the mean-variance approach far more often than the meansemivariance approach, despite the fact that semivariance is often considered a more plausible measure of risk than variance. The popularity of the mean-variance approach follows in part from the fact that mean-variance problems have well-known closed-form solutions, whereas meansemivari...

Stochastic sequential bargaining games (Merlo and Wilson (1995, 1998)) have found wide applications in various …elds including political economy and macroeconomics due to their ‡exibility in explaining delays in reaching an agreement. In this paper, we present new results in nonparametric identi…cation of such models under di¤erent scenarios of data availability. First, we give conditions for a...

We study different choices of search direction for primal-dual interior-point methods for semidefinite programming problems. One particular choice we consider comes from a specialization of a class of algorithms developed by Nesterov and Todd for certain convex programming problems. We discuss how the search directions for the Nesterov-Todd (NT) method can be computed efficiently and demonstrat...