Results 71 to 80 of about 10,056 (177)
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
Graph rigidity for unitarily invariant matrix norms
, 2020 A rigidity theory is developed for bar-joint frameworks in linear matrix spaces endowed with a unitarily invariant norm. Analogues of Maxwell's counting criteria are obtained and minimally rigid matrix frameworks are shown to belong to the matroidal ...
Kitson, Derek, Levene, Rupert H.
core
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
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
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Some operator inequalities for unitarily invariant norms [PDF]
, 2005 Let L(H) be the algebra of bounded operators on a complex separable Hilbert space H. Let N be a unitarily invariant norm defined on a norm ideal J ⊆ L(H). Given two positive invertible operators P,Q ∊ L(H) and k ∊ (−2, 2], we show that N (PTQ−1 + P−1TQ +
Mosconi, Irene +2 more
core +1 more source
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
On some variational problems in the theory of unitarily invariant norms and Hadamard products
, 2001 We deal with two recent conjectures of R.-C. Li [Linear Algebra Appl. 278 (1998) 317–326], involving unitarily invariant norms and Hadamard products.
Romeo, M. +5 more
core +1 more source
A note on the magnetic Steklov operator on functions
Mathematika, Volume 71, Issue 4, October 2025.Abstract We consider the magnetic Steklov eigenvalue problem on compact Riemannian manifolds with boundary for generic magnetic potentials and establish various results concerning the spectrum. We provide equivalent characterizations of magnetic Steklov operators which are unitarily equivalent to the classical Steklov operator and study bounds for the ...
Tirumala Chakradhar +3 more
wiley +1 more source
Unitarily invariant norm inequalities for some means [PDF]
Journal of Inequalities and Applications, 2014 We introduce some symmetric homogeneous means, and then show unitarily invariant norm inequalities for them, applying the method established by Hiai and Kosaki. Our new inequalities give the tighter bounds of the logarithmic mean than the inequalities given by Hiai and Kosaki.
openaire +3 more sources
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
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