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This is the last article in a series of three initiated by the second author. We elaborate on the concepts and theorems constructed in the previous articles. In particular, we prove that the GH and the GGH uniformities previously introduced…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Luca Bombelli , Johan Noldus

We study the best coapproximation problem in Banach spaces, by using Birkhoff-James orthogonality techniques. We introduce two special types of subspaces, christened the anti-coproximinal subspaces and the strongly anti-coproximinal…

Functional Analysis · Mathematics 2024-08-14 Shamim Sohel , Souvik Ghosh , Debmalya Sain , Kallol Paul

The maximal roundness of a metric space is a quantity that arose in the study of embeddings and renormings. In the setting of Banach spaces, it was shown by Enflo that roundness takes on a much simpler form. In this paper we provide simple…

Functional Analysis · Mathematics 2021-09-16 Alireza Amini-Harandi , Ian Doust , Gavin Robertson

We analyze smooth nonlinear mappings for Hilbert and Banach spaces that carry small balls to convex sets, provided that the radius of the balls is small enough. Being focused on the study of new and mild sufficient conditions for a…

Functional Analysis · Mathematics 2024-03-18 Yarema A. Prykarpatskyy , Petro Ya. Pukach , Myroslava I. Vovk , Michal Greguš

In the present note, the Banach contraction principle is proved in complete modular spaces via an order theoretic approach.

Classical Analysis and ODEs · Mathematics 2013-05-06 Kourosh Nourouzi

A polarity notion for sets in a Banach space is introduced in such a way that the second polar of a set coincides with the smallest strongly convex set with respect to R that contains it. Strongly convex sets are characterized in terms of…

Functional Analysis · Mathematics 2025-08-05 Juan Enrique Martínez-Legaz

By iterative techniques,we present two fixed point theorems, whose modular formulations are relatively close to the Banach's fixed point theorem in the normed spaces.The first result concerns the fixed point of the strongly contraction…

Functional Analysis · Mathematics 2016-09-07 Hanebaly Elaidi

We review the current state of the homogeneous Banach space problem. We then formulate several questions which arise naturally from this problem, some of which seem to be fundamental but new. We give many examples defining the bounds on the…

Functional Analysis · Mathematics 2016-09-06 Peter G. Casazza

The purpose of this paper is devoted to studying representation of measures of non generalized compactness, in particular, measures of noncompactness, of non-weak compactness, and of non-super weak compactness, etc, defined on Banach spaces…

Functional Analysis · Mathematics 2021-03-15 Xiaoling Chen , Lixin Cheng

Within the framework of complex supergeometry and motivated by two-dimensional genus-zero holomorphic N=2 superconformal field theory, we define the moduli space of N=2 super-Riemann spheres with oriented and ordered half-infinite tubes (or…

Quantum Algebra · Mathematics 2007-05-23 Katrina Barron

In this article, we introduce the concept of weakly uniquely stationary representations. This framework enables us to investigate the complementability of closed subspaces within the context of continuous cohomology with coeffcients in…

Functional Analysis · Mathematics 2025-07-14 Mario Klisse

We prove that the following three properties for a Banach space are all different from each other: every finite convex combination of slices of the unit ball is (1) relatively weakly open, (2) has nonempty interior in relative weak topology…

Functional Analysis · Mathematics 2017-03-10 Rainis Haller , Paavo Kuuseok , Märt Põldvere

We prove that Banach spaces $\ell_1\oplus_2\mathbb{R}$ and $X\oplus_\infty Y$, with strictly convex $X$ and $Y$, have plastic unit balls (we call a metric space plastic if every non-expansive bijection from this space onto itself is an…

Functional Analysis · Mathematics 2021-11-22 Rainis Haller , Nikita Leo , Olesia Zavarzina

We introduce a new class of quasi-Banach spaces as an extension of the classical Grand Lebesgue Spaces for small values of the parameter, and we investigate some its properties, in particular, completeness, fundamental function, operators…

Functional Analysis · Mathematics 2020-08-07 Maria Rosaria Formica , Eugeny Ostrovsky , Leonid Sirota

The paper provides a detailed study of crucial inequalities for smoothness and interpolation characteristics in rearrangement invariant Banach function spaces. We present a unified approach based on Holmstedt formulas to obtain these…

Functional Analysis · Mathematics 2024-03-05 Amiran Gogatishvili , Bohumir Opic , Sergey Tikhonov , Walter Trebels

We define and study ordinary differential equations (ODEs) for functions valued in a Banach module $V$ over a finite-dimensional $\Bbbk$-algebra $\mathit{\Lambda}$ by using the tensor of Banach modules. Furthermore, we show that the…

Functional Analysis · Mathematics 2026-05-12 Shengda Liu , Yu-Zhe Liu , Keyu Tao

In this article we introduce the new modulus $\triangle'_{X,\phi}(\varepsilon)$, for which we prove that in the general case is different from the classical modulus of noncompact convexity. The main result of the paper is showing the…

Functional Analysis · Mathematics 2021-11-25 Amra Reki\' c-Vukovi\' c , Nermin Okičić

We survey recent advances in the theory of moduli spaces of stable sheaves on hyperk\"ahler manifolds of dimension greater than $2$. We start by recalling the well-known theory in dimension $2$, i.e.~for $K3$ surfaces, emphasizing the…

Algebraic Geometry · Mathematics 2026-02-27 Kieran G. O'Grady

This paper addresses the study and characterizations of variational convexity of extended-real-valued functions on Banach spaces. This notion has been recently introduced by Rockafellar, and its importance has been already realized and…

Optimization and Control · Mathematics 2023-08-29 Pham Duy Khanh , Vu Vinh Huy Khoa , Boris S. Mordukhovich , Vo Thanh Phat

These are notes of my lectures given at the school on intersection theory and moduli at the ICTP, Trieste. We construct moduli spaces of K3 surfaces and higherdimensional hyperkaehler manifolds, including moduli spaces of (2,2)-conformal…

Algebraic Geometry · Mathematics 2007-05-23 Daniel Huybrechts