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The variation of spectral subspaces for linear self-adjoint operators under an additive bounded perturbation is considered. The objective is to estimate the norm of the difference of two spectral projections associated with isolated parts…

Spectral Theory · Mathematics 2022-02-02 Albrecht Seelmann

This article improves the triangle inequality for complex numbers, using the Hermite-Hadamard inequality for convex functions. Then, applications of the obtained refinement are presented to include some operator inequalities. The operator…

Functional Analysis · Mathematics 2022-04-19 Shigeru Furuichi , Mohammad Sababheh , Hamid Reza Moradi

New symmetries, norm computations and spectral information are obtained for the Leray transform on a class of unbounded hypersurfaces in $\mathbb{C}^2$. Emphasis is placed on certain distinguished measures, with results on operator norm…

Complex Variables · Mathematics 2025-05-28 Luke D. Edholm , Yonatan Shelah

In this note we revisit the classical geometric-arithmetic mean inequality and find a formula for the difference of the arithmetic and the geometric means of given $n\in\mathbb N$ nonnegative numbers $x_1,x_2,\dots,x_n$. The formula yields…

Classical Analysis and ODEs · Mathematics 2017-01-03 Davit Harutyunyan

If T is a bounded linear operator acting on an infinite-dimensional Banach space, then there exists and operator F of rank at most one and arbitrarily small norm such that T-F has an invariant subspace of infinite dimension and codimension.…

Functional Analysis · Mathematics 2020-06-19 Vladimir Muller

Many of the technical complications associated with the general theory of relativity ultimately stem from the nonlinearity of Einstein's equation. It is shown here that an appropriate choice of dynamical variables may be used to eliminate…

General Relativity and Quantum Cosmology · Physics 2015-01-07 Abraham I. Harte

A random vector whose norm and overlap (inner product with an independent copy) concentrates is shown to have random low-dimensional projections that are approximately random Gaussians. Conversely, asymptotically random Gaussian projections…

Probability · Mathematics 2025-12-23 Timothy L. H. Wee , Sekhar Tatikonda

We discuss relations between uniform minimality, unconditionality and interpolation for families of reproducing kernels in backward shift invariant subspaces. This class of spaces contains as prominent examples the Paley-Wiener spaces for…

Complex Variables · Mathematics 2009-01-23 Eric Amar , Andreas Hartmann

In this work, we investigate the Cauchy problem for the spatially inhomogeneous non-cutoff Kac equation. If the initial datum belongs to the spatially critical Besov space, we can prove the well-posedness of weak solution under a…

Analysis of PDEs · Mathematics 2019-02-19 Hongmei Cao , Hao-Guang Li , Chao-Jiang Xu , Jiang Xu

We give simple conditions implying the well-posedness of the Cauchy problem for the propagation of classical scalar fields in general (n+2)-dimensional static and spherically symmetric spacetimes. They are related to properties of the…

General Relativity and Quantum Cosmology · Physics 2013-11-05 Ricardo E. Gamboa Saraví , Marcela Sanmartino , Philippe Tchamitchian

Rays are classes of an equivalence relation on a module V over a supertropical semiring. They provide a version of convex geometry, supported by a "supertropical trigonometry" and compatible with quasilinearity, in which the CS-ratio takes…

Rings and Algebras · Mathematics 2019-10-01 Zur Izhakian , Manfred Knebusch

We provide a concise proof of existence for nonlinear operator equations in separable Banach spaces. Notably, the operator is not assumed to be monotone. Instead, our main hypotheses consist of a continuity assumption and a generalized…

Analysis of PDEs · Mathematics 2025-03-21 Roland Becker , Malte Braack

A quadrilateral inequality established by C. Sch\"otz in the context of Hilbert spaces is extended to the framework of Banach spaces. Our approach is based on the majorization theory and a substitute for the parallelogram law associated…

Functional Analysis · Mathematics 2024-08-16 Constantin P. Niculescu

In the present paper, we obtain the basic Chen inequalities for submanifolds of quaternion Kaehler-like statistical manifolds. Also, we discuss the same inequality for Lagrangian submanifolds.

Differential Geometry · Mathematics 2020-02-20 Mohamd Saleem Lone , Mehraj Ahmad Lone

For any positive invertible matrix $A$ and any normal matrix $B$ in $M_{n}({\Bbb C})$, we investigate whether the inequality $ ||A\sharp (B^{*}A^{-1}B)||\geq ||B|| $ is true or not, where $\sharp$ denotes the geometric mean and $||\cdot||$…

Functional Analysis · Mathematics 2017-10-18 Tomohiro Hayashi

It is well known that iterates of quasi-compact operators converge towards a spectral projection, whereas the explicit construction of the limiting operator is in general hard to obtain. Here, we show a simple method to explicitly construct…

Functional Analysis · Mathematics 2017-06-05 Johannes Nagler

In this short note, we first consider some inequalities for comparison of some algebraic properties of two continuous algebra-multiplications on an arbitrary Banach space and then, as an application, we consider some very basic observations…

Functional Analysis · Mathematics 2019-07-24 Maysam Maysami Sadr

In this paper, we consider the first order Hardy inequalities using simple equalities. This basic setting not only permits to derive quickly many well-known Hardy inequalities with optimal constants, but also supplies improved or new…

Analysis of PDEs · Mathematics 2021-12-14 Xia Huang , Dong Ye

We give some new refinements of Heinz inequality and an improvement of the reverse Young's inequality for scalars and we use them to establish new inequalities for operators and the Hilbert-Schmidt norm of matrices. We give a uniformly and…

Functional Analysis · Mathematics 2017-03-09 A. G. Ghazanfari , S. Malekinejad , S. Talebi

We consider interpolation inequalities for imbeddings of the $l^2$-sequence spaces over $d$-dimensional lattices into the $l^\infty_0$ spaces written as interpolation inequality between the $l^2$-norm of a sequence and its difference. A…

Analysis of PDEs · Mathematics 2014-07-03 Alexei Ilyin , Ari Laptev , Sergey Zelik