We present an explicit pseudorandom generator for oblivious, read-once, width-3 branching programs, which can read their input bits in any order. The generator has seed length Õ(log3 n). The previously best known seed length for this model is n1/2+o(1) due to Impagliazzo, Meka, and Zuckerman (FOCS ’12). Our work generalizes a recent result of Reingold, Steinke, and Vadhan (RANDOM ’13) for permu...

We prove upper and lower bounds and give an approximation algorithm for the cover time of the random walk on a graph. We introduce a parameter M motivated by the well known Matthews bounds on the cover time and prove that M/2 ≤ C = O(M (ln ln n) 2). We give a deterministic polynomial time algorithm to approximate M within a factor of 2; this then approximates C within a factor of O((ln ln n) 2)...

The purpose of this note is to give a necessary and sufficient condition for a semicharacter on a subsemigroup of a commutative semigroup G to be extendable to a semicharacter on G. A bounded complex function x on a semigroup G is called a semicharacter of G if x(x)9^0 for some xEG and x(xy) = x(%)x(y) ior all x, yEG. Semicharacters were introduced by Hewitt and Zuckerman [l] and in a slightly ...

Patent assertion entities, sometimes known as ‘patent trolls,’ do not manufacture goods themselves but profit from licensing agreements that they often enforce via the threat of litigation. This paper explores empirically how litigation by one such patent troll affected the sales of medical imaging technology. It finds evidence that relative to similar products, made by the same firm, but not c...

This review describes how measures of a prominent three-dimensional hierarchical model of personality traits relate to substance use. H. J. Eysenck proposed a biologically based model of personality that gave rise to related models such as those of J. A. Gray, C. R. Cloninger, and M. Zuckerman. The varying role of impulsivity--a trait related to disinhibition, approach motivation, novelty seeki...

Since 1984, when Cole and Zuckerman referred to gender differences in productivity among academic scientists as a puzzle, sociologists have sought to explain these differences by incorporating primarily institutional-level factors. In addition to these factors, the author contends that an undertheorized and heretofore unmeasured concept—the extent of research specialization—can also help explai...

To each category C of modules of finite length over a complex simple Lie algebra g, closed under tensoring with finite dimensional modules, we associate and study a category AFF(C)κ of smooth modules (in the sense of Kazhdan and Lusztig [9]) of finite length over the corresponding affine Kac– Moody algebra in the case of central charge less than the critical level. Equivalent characterizations ...

Chairman Johnson and members of the committee, I appreciate the opportunity to appear before you today to discuss the geographic practice costs adjustment in the Medicare Physician Fee Schedule. My name is Stephen Zuckerman and I am a Principal Research Associate at the Urban Institute, a non-profit, non-partisan research institute located in Washington, D.C. Along with Gregory Pope at the Cent...

For every n and 0 < δ < 1, we construct graphs on n nodes such that every two sets of size n share an edge, having essentially optimal maximum degree n1−δ+o(1). Using known and new reductions from these graphs, we explicitly construct: 1. A k round sorting algorithm using n comparisons. 2. A k round selection algorithm using n −1)+o(1) comparisons. 3. A depth 2 superconcentrator of size n. 4. A...

The first part of this article describes a study of the relationships between personality and risk-taking in six areas: smoking, drinking, drugs, sex, driving, and gambling. The participants, 260 college students, were given self-report measures of risky behaviors in each of the six areas and the Zuckerman-Kuhlman five-factor personality questionnaire. Generalized risk-taking (across all six ar...