Results 81 to 90 of about 581 (209)
Numerical Linear Algebra with Applications, Volume 32, Issue 6, December 2025.ABSTRACT In this work, we propose a novel preconditioned minimal residual method for a class of real, nonsymmetric multilevel block Toeplitz systems, which generalizes an ideal preconditioner established in [J. Pestana. Preconditioners for symmetrized Toeplitz and multilevel Toeplitz matrices. SIAM Journal on Matrix Analysis and Applications, 40(3):870–
Grigorios Tachyridis, Sean Y. Hon
wiley +1 more source
Inequalities involving unitarily invariant norms and operator monotone functions
, 2002 Let ∥·∥ be a unitarily invariant norm on matrices. For matrices A,B,X with A,B positive semidefinite and X arbitrary, we prove that the function t↦∥|AtXB1−t|r∥·∥|A1−tXBt|r∥ is convex on [0,1] for each r>0.
Hiai, FM +5 more
core +1 more source
Arbitrary unitarily invariant random matrix ensembles and supersymmetry
, 2006 We generalize the supersymmetry method in random matrix theory to ensembles which are unitarily invariant, but otherwise arbitrary. Our exact approach extends a previous contribution in which we constructed a supersymmetric representation for the class ...
Guhr, Thomas, Thomas Guhr
core +2 more sources
Conformal optimization of eigenvalues on surfaces with symmetries
Journal of the London Mathematical Society, Volume 112, Issue 6, December 2025.Abstract Given a conformal action of a discrete group on a Riemann surface, we study the maximization of Laplace and Steklov eigenvalues within a conformal class, considering metrics invariant under the group action. We establish natural conditions for the existence and regularity of maximizers. Our method simplifies the previously known techniques for
Denis Vinokurov
wiley +1 more source
, 1995 An arithmetic-geometric mean inequality for unitarily invariant norms and matrices,2∥A∗XB∥⩽∥AA∗X+XBB∗∥,is an immediate consequence of a basic inequality for singular values of Hadamard ...
Horn, Roger A.
core +1 more source
Boundary representations of locally compact hyperbolic groups
Proceedings of the London Mathematical Society, Volume 131, Issue 6, December 2025.Abstract We develop the theory of Patterson–Sullivan measures for locally compact hyperbolic groups. This theory associates to certain left‐invariant metrics on the group measures on its boundary. Next, we establish irreducibility of the resulting (unitary) Koopman representations for second countable, nonelementary, unimodular locally compact ...
Michael Glasner
wiley +1 more source
Residual bounds for unitarily invariant norms on clustered eigenvalues
, 1997 Let n × n Hermitian matrix A have eigenvalues λ1, λ2, …, λn, let k × k Hermitian matrix H have eigenvalues μ1, μ2, …, μk, and let Q be an n × k matrix having full column rank, so 1 ≤ k ≤ n. It is proved that there exist k eigenvalues λi1 ≤ λi2 … ≤ λik of
Xie, Jian-Jun, Jian-Jun Xie
core +1 more source
Sensitivity of Perron and Fiedler Eigenpairs to Structural Perturbations of a Network
Numerical Linear Algebra with Applications, Volume 32, Issue 5, October 2025.ABSTRACT One can estimate the change of the Perron and Fiedler values for a connected network when the weight of an edge is perturbed by analyzing relevant entries of the Perron and Fiedler vectors. This is helpful for identifying edges whose weight perturbation causes the largest change in the Perron and Fiedler values.
Silvia Noschese, Lothar Reichel
wiley +1 more source
Interpolated inequalities for unitarily invariant norms
Linear Algebra and its Applications, 2015 zbMATH Open Web Interface contents unavailable due to conflicting licenses.
openaire +2 more sources
Dirac–Schrödinger operators, index theory and spectral flow
Journal of the London Mathematical Society, Volume 112, Issue 4, October 2025.Abstract In this article, we study generalised Dirac–Schrödinger operators in arbitrary signatures (with or without gradings), providing a general KK$\textnormal {KK}$‐theoretic framework for the study of index pairings and spectral flow. We provide a general Callias Theorem, which shows that the index (or the spectral flow, or abstractly the K ...
Koen van den Dungen
wiley +1 more source