1,721,000 research outputs found

    The minimal spherical dispersion

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    We prove upper and lower bounds on the minimal spherical dispersion, improving upon previous estimates obtained by Rote and Tichy [Spherical dispersion with an application to polygonal approximation of curves, Anz. Österreich. Akad. Wiss. Math.-Natur. Kl. 132 (1995), 3--10]. In particular, we see that the inverse N(ε,d)N(\varepsilon,d) of the minimal spherical dispersion is, for fixed ε>0\varepsilon>0, linear in the dimension dd of the ambient space. We also derive upper and lower bounds on the expected dispersion for points chosen independently and uniformly at random from the Euclidean unit sphere. In terms of the corresponding inverse N~(ε,d)\widetilde{N}(\varepsilon,d), our bounds are optimal with respect to the dependence on ε\varepsilon

    Combinatorial Inequalities and Sub-spaces of L1

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    Non UBCUnreviewedAuthor affiliation: University of AlbertaPostdoctora

    Musielak-Orlicz spaces that are isomorphic to subspaces of L1

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    We prove that 1/n! ∑π∈Gn (∑ni=1 |xiai,π(i)|2)1/2 is equivalent to a Musielak-Orlicz norm ||x||∑Mi. We also provide the converse result, i.e., given the Orlicz functions, we provide a formula for the choice of the matrix that generates the corresponding Musielak-Orlicz norm. As a consequence, we obtain the embedding of 2-concave Musielak-Orlicz spaces into L1

    New Perspectives and Computational Challenges in High Dimensions

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    High-dimensional systems are frequent in mathematics and applied sciences, and the understanding of high-dimensional phenomena has become increasingly important. The mathematical subdisciplines most strongly related to such phenomena are functional analysis, convex geometry, and probability theory. In fact, a new area emerged, called asymptotic geometric analysis, which is at the very core of these disciplines and bears a number of deep connections to mathematical physics, numerical analysis, and theoretical computer science. The last two decades have seen a tremendous growth in this area. Far reaching results were obtained and various powerful techniques have been developed, which rather often have a probabilistic flavor. The purpose of this workshop was to explored these new perspectives, to reach out to other areas concerned with high-dimensional problems, and to bring together researchers having different angles on high-dimensional phenomena

    Teilräume von L1 und kombinatorische Ungleichungen in der Banachraumtheorie

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    Die Arbeit beschäftigt sich mit endlich-dimensionalen, symmetrischen Teilräumen von L1. Diese werden mit Hilfe kombinatorischer Ungleichungen studiert und es wird eine neue Klasse endlich-dimensionaler, symmetrischer Teilräume von L1 angeben. Außerdem werden in der Arbeit Musielak-Orlicz Räume studiert und in zwei Kapiteln werden kombinatorische Ungleichungen bewiesen

    The large and moderate deviations approach in geometric functional analysis

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    The work of Gantert, Kim, and Ramanan [Large deviations for random projections of p\ell^p balls, Ann. Probab. 45 (6B), 2017] has initiated and inspired a new direction of research in the asymptotic theory of geometric functional analysis. The moderate deviations perspective, describing the asymptotic behavior between the scale of a central limit theorem and a large deviations principle, was later added by Kabluchko, Prochno, and Th\"ale in [High-dimensional limit theorems for random vectors in pn\ell_p^n balls. II, Commun. Contemp. Math. 23(3), 2021]. These two approaches nicely complement the classical study of central limit phenomena or non-asymptotic concentration bounds for high-dimensional random geometric quantities. Beyond studying large and moderate deviations principles for random geometric quantities that appear in geometric functional analysis, other ideas emerged from the theory of large deviations and the closely related field of statistical mechanics, and have provided new insight and become the origin for new developments. Within less than a decade, a variety of results have appeared and formed this direction of research. Recently, a connection to the famous Kannan-Lov\'asz-Simonovits conjecture and the study of moderate and large deviations for isotropic log-concave random vectors was discovered. In this manuscript, we introduce the basic principles, survey the work that has been done, and aim to manifest this direction of research, at the same time making it more accessible to a wider community of researchers.Comment: 57 pages, 2 figure

    Large deviations for random matrices in the orthogonal group and Stiefel manifold with applications to random projections of product distributions

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    We prove large deviation principles (LDPs) for random matrices in the orthogonal group and Stiefel manifold, determining both the speed and good convex rate functions that are explicitly given in terms of certain log-determinants of trace-class operators and are finite on the set of Hilbert-Schmidt operators MM satisfying MM<1\|MM^*\|<1. As an application of those LDPs, we determine the precise large deviation behavior of kk-dimensional random projections of high-dimensional product distributions using an appropriate interpretation in terms of point processes, also characterizing the space of all possible deviations. The case of uniform distributions on p\ell_p-balls, 1p1\leq p \leq \infty, is then considered and reduced to appropriate product measures. Those applications generalize considerably the recent work [Johnston, Kabluchko, Prochno: Projections of the uniform distribution on the cube - a large deviation perspective, Studia Mathematica 264 (2022), 103-119].Comment: 41 page

    Sharp concentration phenomena in high-dimensional Orlicz balls

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    In this article, we present a precise deviation formula for the intersection of two Orlicz balls generated by Orlicz functions VV and WW. Additionally, we establish a (quantitative) central limit theorem in the critical case and a strong law of large numbers for the WW-norm of the uniform distribution on B(n,V)\mathbb{B}^{(n,V)}. Our techniques also enable us to derive a precise formula for the thin-shell concentration of uniformly distributed random vectors in high-dimensional Orlicz balls. In our approach we establish an Edgeworth-expansion using methods from harmonic analysis together with an exponential change of measure argument.28 pages, 4 figure

    The minimal spherical dispersion

    No full text
    We prove upper and lower bounds on the minimal spherical dispersion, improving upon previous estimates obtained by Rote and Tichy in (Anz Österreich Akad Wiss Math Nat Kl 132:3–10, 1995). In particular, we see that the inverse N(ε,d)of the minimal spherical dispersion is, for fixed ε>0, linear in the dimension d of the ambient space. We also derive upper and lower bounds on the expected dispersion for points chosen independently and uniformly at random from the Euclidean unit sphere. In terms of the corresponding inverse N~(ε,d), our bounds are optimal with respect to the dependence on ε
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