Ahmad El Soufi

  1. Isoperimetric control of the spectrum of a compact hypersurface.

    Authors: Bruno Colbois, Ahmad El Soufi, Alexandre Girouard
    Subjects: Metric Geometry
    Abstract

    Upper bounds for the eigenvalues of the Laplace-Beltrami operator on a
    hypersurface bounding a domain in some ambient Riemannian manifold are given in
    terms of the isoperimetric ratio of the domain. These results are applied to
    the extrinsic geometry of isometric embeddings.

  2. Bounding the eigenvalues of the Laplace-Beltrami operator on compact submanifolds.

    Authors: Bruno Colbois, Emily B. Dryden, Ahmad El Soufi
    Subjects: Metric Geometry
    Abstract

    We give upper bounds for the eigenvalues of the La-place-Beltrami operator of
    a compact $m$-dimensional submanifold $M$ of $\R^{m+p}$. Besides the dimension
    and the volume of the submanifold and the order of the eigenvalue, these bounds
    depend on either the maximal number of intersection points of $M$ with a
    $p$-plane in a generic position (transverse to $M$), or an invariant which
    measures the concentration of the volume of $M$ in $\R^{m+p}$. These bounds are
    asymptotically optimal in the sense of the Weyl law.

  3. Bounding the eigenvalues of the Laplace-Beltrami operator on compact submanifolds.

    Authors: Bruno Colbois, Emily B. Dryden, Ahmad El Soufi
    Subjects: Metric Geometry
    Abstract

    We give upper bounds for the eigenvalues of the La-place-Beltrami operator of
    a compact $m$-dimensional submanifold $M$ of $\R^{m+p}$. Besides the dimension
    and the volume of the submanifold and the order of the eigenvalue, these bounds
    depend on either the maximal number of intersection points of $M$ with a
    $p$-plane in a generic position (transverse to $M$), or an invariant which
    measures the concentration of the volume of $M$ in $\R^{m+p}$. These bounds are
    asymptotically optimal in the sense of the Weyl law.

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