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We introduce and analyze a natural geometric version of Renegar's condition number R for the homogeneous convex feasibility problem associated with a regular cone C subseteq R^n. Let Gr_{n,m} denote the Grassmann manifold of m-dimensional…

Optimization and Control · Mathematics 2012-11-06 Dennis Amelunxen , Peter Bürgisser

A necessary and sufficient condition for the convergence of an infinite right product of matrices of the form | I B | A = | 0 C |, with (uniformly) contracting submatrices $C$, is proven.

Rings and Algebras · Mathematics 2007-05-23 Olga Holtz

This paper explores the concept of approximate Birkhoff-James orthogonality in the context of operators on semi-Hilbert spaces. These spaces are generated by positive semi-definite sesquilinear forms. We delve into the fundamental…

Functional Analysis · Mathematics 2023-12-19 Cristian Conde , Kais Feki

We present an expression for the right hand derivative of the $\mathcal{B(H,K)}$ norm generalizing the result for $\mathcal{K}=\mathcal{H}$ in [D. J. Ke$\check{\mathrm{c}}$ki$\grave{\mathrm{c}}$, Gateaux derivative of $B(H)$ norm, Proc.…

Functional Analysis · Mathematics 2026-05-25 Priyanka Grover , Krishna Kumar Gupta , Susmita Seal

We introduce a general class of transport distances ${\rm WB}_{\Lambda}$ over the space of positive semi-definite matrix-valued Radon measures $\mathcal{M}(\Omega,\mathbb{S}_+^n)$, called the weighted Wasserstein-Bures distance. Such a…

Numerical Analysis · Mathematics 2023-10-18 Bowen Li , Jun Zou

We describe additive surjections on direct sum of matrix algebras that preserve singularity in one direction. As an application, we classify additive surjections on finite-dimensional $C^\ast$-algebras that preserve mutual strong…

Rings and Algebras · Mathematics 2026-05-12 Bojan Kuzma , Srdjan Stefanović

In this paper, we study Birkhoff-James orthogonality of bounded linear operators and give a complete characterization of Birkhoff-James orthogonality of bounded linear operators on infinite dimensional real normed linear spaces. As an…

Functional Analysis · Mathematics 2024-08-13 Debmalya Sain , Kallol Paul , Arpita Mal

We study the relationship between the point-wise symmetry of Birkhoff-James orthogonality and the geometry of the space of operators $\mathbb{B}(\ell_\infty^n,\ell_1^m)$. We show that any non-zero left-symmetric point in this space is a…

Functional Analysis · Mathematics 2022-11-17 Babhrubahan Bose

Given a bilinear form on $\mathbb C^n$, represented by a matrix $A\in\mathbb C^{n\times n}$, the problem of finding the largest dimension of a subspace of $\mathbb C^n$ such that the restriction of $A$ to this subspace is a non-degenerate…

Rings and Algebras · Mathematics 2022-03-15 Alberto Borobia , Roberto Canogar , Fernando De Terán

In this paper, we provide an algebraic condition on any $2n \times 2n$ real symmetric positive definite matrix which is necessary and sufficient for the matrix to be diagonalized by an orthosymplectic matrix in the sense of Williamson's…

Functional Analysis · Mathematics 2024-03-22 Hemant K. Mishra

Given two rational univariate polynomials, the Wasserstein distance of their associated measures is an algebraic number. We determine the algebraic degree of the squared Wasserstein distance, serving as a measure of algebraic complexity of…

Algebraic Geometry · Mathematics 2024-01-24 Chiara Meroni , Bernhard Reinke , Kexin Wang

In this paper, the concept of Birkhoff--James orthogonality of operators on a Hilbert space is generalized when a semi-inner product is considered. More precisely, for linear operators $T$ and $S$ on a complex Hilbert space $\mathcal{H}$, a…

Functional Analysis · Mathematics 2019-05-13 Ali Zamani

We introduce the notion of approximate smoothness in a normed linear space. We characterize this property and show the connections between smoothness and approximate smoothness for some spaces. As an application, we consider in particular…

Functional Analysis · Mathematics 2022-11-08 Jacek Chmieliński , Divya Khurana , Debmalya Sain

In this article, the relationship between Birkhoff-James orthogonality of elementary tensors in certain tensor product spaces with the Birkhoff-James orthogonality of individual elements in their respective spaces is studied.

Functional Analysis · Mathematics 2022-10-26 Mohit , Ranjana Jain

Two different notions of approximate Birkhoff-James orthogonality in nor\-med linear spaces have been introduced by Dragomir and Chmie\-li\'n\-ski. In the present paper we consider a global and a local approximate symmetry of the…

Functional Analysis · Mathematics 2020-12-16 Jacek Chmieliński , Divya Khurana , Debmalya Sain

We study the norm derivatives in the context of Birkhoff-James orthogonality in real Banach spaces. As an application of this, we obtain a complete characterization of the left-symmetric points and the right-symmetric points in a real…

Functional Analysis · Mathematics 2020-09-25 Divya Khurana , Debmalya Sain

We present necessary and sufficient conditions for an n\times n complex matrix B to be unitarily similar to a fixed unicellular (i.e., indecomposable by similarity) n\times n complex matrix A

Representation Theory · Mathematics 2015-03-17 Douglas Farenick , Tatiana G. Gerasimova , Nadya Shvai

In this brief note, it is shown that the Bures-Wasserstein (BW) metric on the space positive definite matrices lends itself to convex optimization. In other words, the computation of the BW metric can be posed as a convex optimization…

Optimization and Control · Mathematics 2023-03-08 Shravan Mohan

We combine functional analytic and geometric viewpoints on approximate Birkhoff and isosceles orthogonality in generalized Minkowski spaces which are finite-dimensional vector spaces equipped with a gauge. This is the first approach to…

Metric Geometry · Mathematics 2017-07-18 Thomas Jahn

We introduce the notion of orthogonality in a vector space with a topology on it. To serve our purpose, we define orthogonality space for a given vector space X, using the topology on it. We show that for a suitable choice of orthogonality…

Functional Analysis · Mathematics 2019-10-28 Debmalya Sain , Saikat Roy , Kallol Paul