795 research outputs found

    Self-adjointness of perturbed bi-Laplacians on infinite graphs

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    We give a sufficient condition for the essential self-adjointness of a perturbation of the square of the magnetic Laplacian on an infinite weighted graph. The main result is applicable to graphs whose degree function is not necessarily bounded. The result allows perturbations that are not necessarily bounded from below by a constant.Comment: We edited the introduction and updated the bibliographical information for some references. We moved the examples towards the front of the articl

    Self-adjoint extensions of differential operators on Riemannian manifolds

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    We study H=D∗D+VH=D^*D+V, where DD is a first order elliptic differential operator acting on sections of a Hermitian vector bundle over a Riemannian manifold MM, and VV is a Hermitian bundle endomorphism. In the case when MM is geodesically complete, we establish the essential self-adjointness of positive integer powers of HH. In the case when MM is not necessarily geodesically complete, we give a sufficient condition for the essential self-adjointness of HH, expressed in terms of the behavior of VV relative to the Cauchy boundary of MM

    Maximal accretive extensions of Schr\"odinger operators on vector bundles over infinite graphs

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    Given a Hermitian vector bundle over an infinite weighted graph, we define the Laplacian associated to a unitary connection on this bundle and study the essential self-adjointness of a perturbation of this Laplacian by an operator-valued potential. Additionally, we give a sufficient condition for the resulting Schr\"odinger operator to serve as the generator of a strongly continuous contraction semigroup in the corresponding l^{p}-space.Comment: We have made significant revisions of the previous version. In particular, this version has a new title: "Maximal Accretive Extensions of Schr\"odinger Operators on Vector Bundles over Infinite Graphs." The final version will appear in Integral Equations and Operator Theory and will be availableat Springer via http://dx.doi.org/10.1007/s00020-014-2196-

    Essential self-adjointness of Schroedinger type operators on manifolds

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    We obtain several essential self-adjointness conditions for a Schroedinger type operator D*D+V acting in sections of a vector bundle over a manifold M. Here V is a locally square-integrable bundle map. Our conditions are expressed in terms of completeness of certain metrics on M; these metrics are naturally associated to the operator. We do not assume a priori that M is endowed with a complete Riemannian metric. This allows us to treat e.g. operators acting on bounded domains in the euclidean space. For the case when the principal symbol of the operator is scalar, we establish more precise results. The proofs are based on an extension of the Kato inequality which modifies and improves a result of Hess, Schrader and Uhlenbrock.Comment: 52 pages, Minor corrections are made; To appear in Russian Math. Survey

    Review of Presumed Incompetent: the Intersections of Race and Class for Women in Academia edited by Gabriella Gutierrez y Muhs et al.

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    Review of Presumed Incompetent: the Intersections of Race and Class for Women in Academia edited by Gabriella Gutierrez y Muhs et al

    Review of Entangled Subjects: Indigenous / Australian Cross-Cultures of Talk, Text and Modernity by Michele Grossman.

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    Review of Entangled Subjects: Indigenous / Australian Cross-Cultures of Talk, Text and Modernity by Michele Grossman

    Review of Am I Black Enough For You? By Anita Heiss

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    Review of Am I Black Enough For You? By Anita Heis
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