Results 41 to 50 of about 99,725 (136)

On Noncommutative and semi-Riemannian Geometry

, 2002
We introduce the notion of a semi-Riemannian spectral triple which generalizes the notion of spectral triple and allows for a treatment of semi-Riemannian manifolds within a noncommutative setting.
Alexander Strohmaier, Baum, Bognar, Cipriani, Connes, Connes, Dixmier, Gracia-Bondia, Hawkins, Kalau, Kastler, Kopf, Landi, O’Neill, Parfionov, Reed, Taylor   +16 more
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Toward Supergravity Spectral Action

, 2013
A spectral action of Euclidean supergravity is proposed. We calculate up to $a_4$, the Seeley-Dewitt coefficients in the expansion of the spectral action associated to the supergravity Dirac operator.
Ciuhu C., J. L. LÓPEZ, M. P. RYAN, M. SABIDO, O. OBREGÓN   +4 more
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Linear instability criteria for ideal fluid flows subject to two subclasses of perturbations

, 2011
In this paper we examine the linear stability of equilibrium solutions to incompressible Euler's equation in 2- and 3-dimensions. The space of perturbations is split into two classes - those that preserve the topology of vortex lines and those in the ...
A. Calderon, A. Grigis, A. Lifschitz, A. Lifschitz, A. Pazy, C. Chicone, Elizabeth Thoren, J. Guckenheimer, J. Saranen, L. Boutet de Monvel, M.A. Shubin, M.M. Vishik, P. Hartman, R. Nussbaum, R. Shvydkoy, R. Shvydkoy, R. Shvydkoy, R. Shvydkoy, R. Shvydkoy, R. Shvydkoy, S. Friedlander, S. Friedlander, S. Friedlander, S. Friedlander, V.I. Arnold, V.I. Arnold, Y. Latushkin   +26 more
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Chiral Asymmetry and the Spectral Action

, 2012
We consider orthogonal connections with arbitrary torsion on compact Riemannian manifolds. For the induced Dirac operators, twisted Dirac operators and Dirac operators of Chamseddine-Connes type we compute the spectral action. In addition to the Einstein-
A. Chamseddine, A. Chamseddine, A. Chamseddine, A. Connes, A. Sitarz, B. Broda, B. Iochum, B. Iochum, Christoph A. Stephan, F. Hanisch, F. Lizzi, F. Pfäffle, F.W. Hehl, F.W. Hehl, Frank Pfäffle, G. Grensing, I. Agricola, I.L. Shapiro, J.L. Kazdan, M. Berger, P. Baekler, P. Baekler, R. Hojman, S. Holst, W.H. Goldthorpe, Yu.N. Obukhov, É. Cartan, É. Cartan, É. Cartan   +28 more
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Inverse spectral theory for symmetric operators with several gaps: scalar-type Weyl functions

Journal of Functional Analysis, 2005
\textit{M. G. Kreǐn} investigated in [Mat. Sb., N. Ser. 20(62), 431--495 (1947; Zbl 0029.14103)] the spectrum of self-adjoint extensions \(\tilde S\) within a gap \(J\) of a densely defined symmetric operator \(S\) with finite deficiency indices. The result was generalized by \textit{J. F. Brasche, H. Neidhardt} and \textit{J. Weidmann} in [Math.
Albeverio, S., Brasche, J.F., Malamud, M.M., Neidhardt, H.   +3 more
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Invertible Dirac operators and handle attachments on manifolds with boundary

, 2014
For spin manifolds with boundary we consider Riemannian metrics which are product near the boundary and are such that the corresponding Dirac operator is invertible when half-infinite cylinders are attached at the boundary.
Adams R. A., Ammann B., Bär C., Kosinski A. A., Lawson H. B., Mattias Dahl, Milnor J., Müller W., Müller W., Nadine Grosse, Walsh M.   +10 more
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On certain spectral features inherent to scalar type spectral operators

, 2016
Important spectral features, such as the emptiness of the residual spectrum, countability of the point spectrum, provided the space is separable, and a characterization of spectral gap at $0$, known to hold for bounded scalar type spectral operators, are shown to naturally transfer to the unbounded case.
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On spectral inclusion and mapping theorems for scalar type spectral operators and semigroups

, 2020
We establish spectral inclusion and mapping theorems for scalar type spectral operators, generalizing their counterparts for normal operators. Thereby, we extend a precise weak spectral mapping theorem, known to hold for $C_0$-semigroups of normal operators on complex Hilbert spaces, to the more general case of $C_0$-semigroups of scalar type spectral ...
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A characterization of the generators of analytic C₀‐semigroups in the class of scalar type spectral operators [PDF]

Abstract and Applied Analysis, 2004
In the class of scalar type spectral operators in a complex Banach space, a characterization of the generators of analytic C0‐semigroups in terms of the analytic vectors of the operators is found.
openaire   +3 more sources

Matrix Measures and Finite Rank Perturbations of Self-adjoint Operators

, 2019
Matrix-valued measures provide a natural language for the theory of finite rank perturbations. In this paper we use this language to prove some new perturbation theoretic results.
Liaw, Constanze, Treil, Sergei
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