17,033 research outputs found

    The Szemeredi-Trotter Theorem in the Complex Plane

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    It is shown that nn points and ee lines in the complex Euclidean plane C2{\mathbb C}^2 determine O(n2/3e2/3+n+e)O(n^{2/3}e^{2/3}+n+e) point-line incidences. This bound is the best possible, and it generalizes the celebrated theorem by Szemer\'edi and Trotter about point-line incidences in the real Euclidean plane R2{\mathbb R}^2.Comment: 24 pages, 5 figures, to appear in Combinatoric

    Asymptotic Normality of Quadratic Estimators

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    We prove conditional asymptotic normality of a class of quadratic U-statistics that are dominated by their degenerate second order part and have kernels that change with the number of observations. These statistics arise in the construction of estimators in high-dimensional semi- and non-parametric models, and in the construction of nonparametric confidence sets. This is illustrated by estimation of the integral of a square of a density or regression function, and estimation of the mean response with missing data. We show that estimators are asymptotically normal even in the case that the rate is slower than the square root of the observations

    The geometry of fractal percolation

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    A well studied family of random fractals called fractal percolation is discussed. We focus on the projections of fractal percolation on the plane. Our goal is to present stronger versions of the classical Marstrand theorem, valid for almost every realization of fractal percolation. The extensions go in three directions: {itemize} the statements work for all directions, not almost all, the statements are true for more general projections, for example radial projections onto a circle, in the case dimH>1\dim_H >1, each projection has not only positive Lebesgue measure but also has nonempty interior. {itemize}Comment: Survey submitted for AFRT2012 conferenc
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