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We prove several results concerning the representation of projections on arbitrary Banach spaces. We also give illustrative examples including an example of a generalized bi-circular projection which can not be written as the average of the…

Functional Analysis · Mathematics 2012-11-02 A. B. Abubaker , Fernanda Botelho , James Jamison

Let $M$ and $N$ be two unital JB$^*$-algebras and let $\mathcal{U} (M)$ and $\mathcal{U} (N)$ denote the sets of all unitaries in $M$ and $N$, respectively. We prove that the following statements are equivalent: $(a)$ $M$ and $N$ are…

Operator Algebras · Mathematics 2020-05-12 María Cueto-Avellaneda , Antonio M. Peralta

We obtain boundedness for the bilinear spherical maximal function in a range of exponents that includes the Banach triangle and a range of $L^p$ with $p<1$. We also obtain counterexamples that are asymptotically optimal with our positive…

Classical Analysis and ODEs · Mathematics 2017-04-13 J. A. Barrionevo , Loukas Grafakos , Danqing He , Petr Honzík , Lucas Oliveira

It is shown that two Banach spaces are linearly isometric if and only if the Gromov--Hausdorff distance between them is finite, in particular, zero. The proof is compilative and relies on results obtained by many researchers on the…

Metric Geometry · Mathematics 2026-02-18 S. A. Bogaty , A. A. Tuzhilin

For a space $X$ denote by $C_b(X)$ the Banach algebra of all continuous bounded scalar-valued functions on $X$ and denote by $C_0(X)$ the set of all elements in $C_b(X)$ which vanish at infinity. We prove that certain Banach subalgebras $H$…

Functional Analysis · Mathematics 2015-06-25 M. R. Koushesh

We consider the Banach space consisting of real-valued continuous functions on an arbitrary compact metric space. It is known that for a prevalent (in the sense of Hunt, Sauer and Yorke) set of functions the Hausdorff dimension of the image…

Metric Geometry · Mathematics 2014-10-06 Jonathan M. Fraser , James T. Hyde

The existence of a Banach limit as a translation invariant positive continuous linear functional on the space of bounded scalar sequences which is equal to 1 at the constant sequence (1,1,...,1,...) is proved in a first course on functional…

Functional Analysis · Mathematics 2019-06-12 M. A. Sofi

Let $X$ be a Banach space with a separable dual $X^{*}$. Let $Y\subset X$ be a closed subspace, and $f:Y\to\mathbb{R}$ a $C^{1}$-smooth function. Then we show there is a $C^{1}$ extension of $f$ to $X$.

Functional Analysis · Mathematics 2010-01-28 D. Azagra , R. Fry , L. Keener

In a previous paper the second author introduced a compact topology on the space of closed ideals of a unital Banach algebra A. If A is separable then this topology is either metrizable or else neither Hausdorff nor first countable. Here it…

Functional Analysis · Mathematics 2007-05-23 J. F. Feinstein , D. W. B. Somerset

Targeting at sparse learning, we construct Banach spaces B of functions on an input space X with the properties that (1) B possesses an l1 norm in the sense that it is isometrically isomorphic to the Banach space of integrable functions on…

Machine Learning · Statistics 2015-01-16 Guohui Song , Haizhang Zhang , Fred J. Hickernell

We show that lattice isomorphisms between lattices of slowly oscillating functions on chain-connected proper metric spaces induce coarsely equivalent homeomorphisms. This result leads to a Banach-Stone-like theorem for these lattices.…

General Topology · Mathematics 2025-03-10 Yutaka Iwamoto

It is well known that in the calculus of variations and in optimization there exist many formulations of the fundamental propositions on the attainment of the infima of sequentially weakly lower semicontinuous coercive functions on…

Functional Analysis · Mathematics 2022-05-04 Yan Tang , Shiqing Zhang , Tiexin Guo

All most all the function spaces over real or complex domains and spaces of sequences, that arise in practice as examples of normed complete linear spaces (Banach spaces), are reflexive. These Banach spaces are dual to their respective…

General Mathematics · Mathematics 2022-03-01 Michael Oser Rabin , Duggirala Ravi

For a Banach space $B$ of functions which satisfies for some $m>0$ $$ \max(\|F+G\|_B,\|F-G\|_B) \ge (\|F\|^s_B + m\|G\|^s_B)^{1/s}, \forall F,G\in B \ (*) $$ a significant improvement for lower estimates of the moduli of smoothness…

Classical Analysis and ODEs · Mathematics 2014-03-17 Zeev Ditzian , Andriy Prymak

The main result of this paper is that the space of conformally compact Einstein metrics on a given manifold is a smooth, infinite dimensional Banach manifold, provided it is non-empty, generalizing earlier work of Graham-Lee and Biquard. We…

Differential Geometry · Mathematics 2010-03-16 Michael T. Anderson

We study universal approximation of continuous functionals on compact subsets of products of Hilbert spaces. We prove that any such functional can be uniformly approximated by models that first take finitely many continuous linear…

Machine Learning · Computer Science 2026-02-04 Andrey Krylov , Maksim Penkin

We present a way to turn an arbitrary (unbounded) metric space $\mathcal{M}$ into a bounded metric space $\mathcal{B}$ in such a way that the corresponding Lipschitz-free spaces $\mathcal{F}(\mathcal{M})$ and $\mathcal{F}(\mathcal{B})$ are…

Functional Analysis · Mathematics 2022-11-01 Fernando Albiac , Jose L. Ansorena , Marek Cuth , Michal Doucha

We prove that if a geodesic metric measure space satisfies a comparison condition for isoperimetric profile and if the observable variance is maximal, then the space is foliated by minimal geodesics, where the observable variance is defined…

Metric Geometry · Mathematics 2018-01-08 Hiroki Nakajima , Takashi Shioya

In this paper it will be shown that assuming the Continuum Hypothesis (CH) every nonreflexive Banach space ultrapower is isometrically isomorphic to the space of continuous, bounded and real-valued functions on the Parovicenko space. This…

Logic · Mathematics 2011-07-11 Piotr Wilczek

According to the fundamental work of Yu.V. Prokhorov, the general theory of stochastic processes can be regarded as the theory of probability measures in complete separable metric spaces. Since stochastic processes depending upon a…

Functional Analysis · Mathematics 2017-09-13 György Pál Gehér , Tamás Titkos