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We prove an analogue of the Cauchy integral theorem for hyperholomorphic functions given in three-dimensional domains with non piece-smooth boundaries and taking values in an arbitrary finite-dimensional commutative associative Banach…

Complex Variables · Mathematics 2013-05-21 Sergiy A. Plaksa , Vitalii S. Shpakivskyi

We provide an explicit uniform bound on the local stability of ergodic averages in uniformly convex Banach spaces. Our result can also be viewed as a finitary version in the sense of T. Tao of the Mean Ergodic Theorem for such spaces and so…

Dynamical Systems · Mathematics 2008-04-30 Ulrich Kohlenbach , Laurentiu Leustean

We consider the stochastic Allen-Cahn equation perturbed by smooth additive Gaussian noise in a spatial domain with smooth boundary in dimension $d\le 3$, and study the semidiscretization in time of the equation by an implicit Euler method.…

Numerical Analysis · Mathematics 2015-08-07 Mihály Kovács , Stig Larsson , Fredrik Lindgren

We show that the Carath\'{e}odory number of the joint numerical range of $d$ many bounded self-adjoint operators is at most $d-1$, and even at most $d-2$ if the underlying Hilbert space has dimension at least $3$. This extension of the…

Functional Analysis · Mathematics 2024-09-10 Beatrice Maier , Tim Netzer

In this paper we study the properties of the normal cone to the proximally smooth set. We give the complete characterization of the proximally smooth set through the monotony properties of its normal cone in an arbitrary uniformly convex…

Functional Analysis · Mathematics 2015-10-05 Grigory Ivanov

We give a new solvability criterion for the boundary Carath\'{e}odory-Fej\'{e}r problem: given a point $x \in \mathbb{R}$ and, a finite set of target values $a^0,a^1,...,a^n \in \mathbb{R}$, to construct a function $f$ in the Pick class…

Complex Variables · Mathematics 2020-04-28 Jim Agler , Zinaida A. Lykova , N. J. Young

We analyze a proof of Bruck to obtain an explicit rate of asymptotic regularity for Ces\`aro means in uniformly convex Banach spaces. Our rate will only depend on a norm bound and a modulus $\eta$ of uniform convexity. One ingredient for…

Dynamical Systems · Mathematics 2022-08-11 Anton Freund , Ulrich Kohlenbach

We give a simple proof of Gromov's Theorem on nilpotentization of vector fields, and exhibit a new method for obtaining quantitative estimates of comparing geometries of two different local Carnot groups in Carnot--Carath\'{e}odory spaces…

Metric Geometry · Mathematics 2008-05-26 Maria Karmanova , Sergey Vodopyanov

A Banach space (or its norm) is said to have the diameter $2$ property (D$2$P in short) if every nonempty relatively weakly open subset of its closed unit ball has diameter $2$. We construct an equivalent norm on $L_1[0,1]$ which is weakly…

Functional Analysis · Mathematics 2022-12-29 Olav Nygaard , Märt Põldvere , Stanimir Troyansky , Tauri Viil

The following theorem is the main result of this note. Theorem 1. Let $(E, \|\cdot\|_E) $ be a rearrangement invariant Banach function space on the interval $[0, 1]$. If $E$ is isometric to $\L_p [0, 1]$ for some $1\le p<\infty$, then $E$…

Functional Analysis · Mathematics 2009-09-25 Yuri A. Abramovich , Mikhail Zaidenberg

Gromov proved a quadratic decay inequality of scalar curvature for a class of complete manifolds. In this paper, we prove that for any uniformly contractible manifold with finite asymptotic dimension, its scalar curvature decays to zero at…

Differential Geometry · Mathematics 2021-06-22 Jinmin Wang , Zhizhang Xie , Guoliang Yu

We establish a quantitative isoperimetric inequality for weighted Riemannian manifolds with $\mathrm{Ric}_{\infty} \ge 1$. Precisely, we give an upper bound of the volume of the symmetric difference between a Borel set and a sub-level (or…

Differential Geometry · Mathematics 2022-02-08 Cong Hung Mai , Shin-ichi Ohta

We study the way in which the Euclidean subspaces of a Banach space fit together, somewhat in the spirit of the Ka\v{s}in decomposition. The main tool that we introduce is an estimate regarding the convex hull of a convex body in John's…

Functional Analysis · Mathematics 2015-05-06 Daniel J. Fresen

We construct a Banach space satisfying that the nearest point map (also called proximity mapping or metric projection) onto any compact and convex subset is continuous but not uniformly continuous. The space we construct is locally…

Functional Analysis · Mathematics 2024-02-08 Rubén Medina , Andrés Quilis

A 1972 duality conjecture due to Pietsch asserts that the entropy numbers of a compact operator acting between two Banach spaces and those of its adjoint are (in an appropriate sense) equivalent. This is equivalent to a dimension free…

Functional Analysis · Mathematics 2007-05-23 S. Artstein , V. Milman , S. J. Szarek , N. Tomczak-Jaegermann

Let $\Tei_{g,n}$ be the Teichm\"uller space of Riemann surfaces of genus $g$ with $n$ punctures. It is conjectured that the Teichm\"uller and Carath\'{e}odory metrics agree on a Teichm\"{u}ller disk if and only if all the zeros of the…

Complex Variables · Mathematics 2026-02-11 Kejie Lin , Weixu Su

Non-convex functions that yet satisfy a condition of uniform convexity for non-close points can arise in discrete constructions. We prove that this sort of discrete uniform convexity is inherited by the convex envelope, which is the key to…

Functional Analysis · Mathematics 2021-05-12 Guillaume Grelier , Matías Raja

We introduce the notion of cotype of a metric space, and prove that for Banach spaces it coincides with the classical notion of Rademacher cotype. This yields a concrete version of Ribe's theorem, settling a long standing open problem in…

Functional Analysis · Mathematics 2012-11-15 Manor Mendel , Assaf Naor

We study the relations between different notions of almost locally uniformly rotund points that appear in literature. We show that every non-reflexive Banach space admits an equivalent norm having a point in the corresponding unit sphere…

Functional Analysis · Mathematics 2026-04-20 Carlo Alberto De Bernardi , Jacopo Somaglia

We introduce the notion of approximate norm attainment set of a bounded linear operator between Banach spaces and use it to obtain a complete characterization of smooth points in the space of compact linear operators, provided the domain…

Functional Analysis · Mathematics 2018-03-19 Debmalya Sain