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  • http://hdl.handle.net/10048/1170
  • Volume distribution and the geometry of high-dimensional random polytopes
  • Pivovarov, Peter
  • en
  • random polytopes
    convex bodies
    log-concave measures
    isotropic constants
    geometric inequalities
  • May 25, 2010 7:57 PM
  • Thesis
  • en
  • Adobe PDF
  • 825680 bytes
  • This thesis is based on three papers on selected topics in Asymptotic Geometric Analysis. The first paper is about the volume of high-dimensional random polytopes; in particular, on polytopes generated by Gaussian random vectors. We consider the question of how many random vertices (or facets) should be sampled in order for such a polytope to capture significant volume. Various criteria for what exactly it means to capture significant volume are discussed. We also study similar problems for random polytopes generated by points on the Euclidean sphere. The second paper is about volume distribution in convex bodies. The first main result is about convex bodies that are (i) symmetric with respect to each of the coordinate hyperplanes and (ii) in isotropic position. We prove that most linear functionals acting on such bodies exhibit super-Gaussian tail-decay. Using known facts about the mean-width of such bodies, we then deduce strong lower bounds for the volume of certain caps. We also prove a converse statement. Namely, if an arbitrary isotropic convex body (not necessarily satisfying the symmetry assumption (i)) exhibits similar cap-behavior, then one can bound its mean-width. The third paper is about random polytopes generated by sampling points according to multiple log-concave probability measures. We prove related estimates for random determinants and give applications to several geometric inequalities; these include estimates on the volume-radius of random zonotopes and Hadamard's inequality for random matrices.
  • Doctoral
  • Doctor of Philosophy
  • Department of Mathematical and Statistical Sciences
  • Fall 2010
  • Tomczak-Jaegermann, Nicole (Mathematical and Statistical Sciences)
  • Litvak, Alexander (Mathematical and Statistical Sciences)
    Troitsky, Vladimir (Mathematical and Statistical Sciences)
    Lau, Anthony To-Ming (Mathematical and Statistical Sciences)
    Yaskin, Vlad (Mathematical and Statistical Sciences)
    Stewart, Lorna (Computing Sciences)
    Werner, Elisabeth (Mathematics, Case Western Reserve University)

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