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We provide an ergodic theorem for certain Banach-space valued functions on structures over $\ZZ^d$, which allow for existence of frequencies of finite patterns. As an application we obtain existence of the integrated density of states for…

Mathematical Physics · Physics 2018-09-28 Daniel Lenz , Peter Mueller , Ivan Veselić

It is shown that if $C$ is a nonempty convex and weakly compact subset of a Banach space $X$ with $M(X)>1$ and $T:C\rightarrow C$ satisfies condition $(C)$ or is continuous and satisfies condition $(C_{\lambda})$ for some $\lambda \in…

Functional Analysis · Mathematics 2015-11-24 Anna Betiuk-Pilarska , Andrzej Wiśnicki

We use $KKM$ theorem to prove the existence of a new fixed point theorem for non-expansive mapping:Let M be a bounded closed convex subset of Hilbert space H, and $A:M\rightarrow M$ be a non-expansive mapping, then exists a fixed point of A…

Functional Analysis · Mathematics 2012-08-07 Chunyan Yang

In this paper, existence of pairs of solutions is obtained for compact potential operators on Hilbert spaces. An application to a second-order boundary value problem is also given as an illustration of our results.

Analysis of PDEs · Mathematics 2024-07-25 A. Mokhtari , K. Saoudi , D. D. Repovš

Two-points nonlocal problem for the first order differential evolution equation with an operator coefficient in a Banach space $X$ is considered. An exponentially convergent algorithm is proposed and justified in assumption that the…

Numerical Analysis · Mathematics 2025-05-06 T. Ju. Bohonova , V. B. Vasylyk

We show that there are no nontrivial surjective uniformly asymptotically regular mappings acting on a metric space and derive some consequences of this fact. In particular, we prove that a jointly continuous left amenable or left reversible…

Functional Analysis · Mathematics 2016-12-20 Sławomir Borzdyński , Andrzej Wiśnicki

We present a constructive proof of Tychonoff's fixed point theorem in a locally convex space for sequentially locally non-constant functions, As a corollary to this theorem we also present Schauder's fixed point theorem in a Banach space…

Logic · Mathematics 2011-05-19 Yasuhito Tanaka

We establish a simple and powerful lemma that provides a criterion for sequences in metric spaces to be Cauchy. Using the lemma, it is then easily verified that the Picard iterates $\{T^nx\}$, where $T$ is a contraction or asymptotic…

General Topology · Mathematics 2016-04-06 Mortaza Abtahi

Let $\mathcal{B} (X)$ be the algebra of all bounded linear operators on an infinite-dimensional complex Banach space $X$. In this note, we show that a lemma used in the proof of the main result of [ Taghavi and Hosseinzadeh, linear and…

Functional Analysis · Mathematics 2024-12-03 S. Elouazzani , M. Elhodaibi , S. Saber

We study properties of continuous semi-homogeneous operators of degree $k$ via various functions (e.g. measures of noncompactness) on all bounded subsets of a Banach space. We prove necessary and sufficient conditions for these functions to…

Functional Analysis · Mathematics 2015-08-19 Nina A. Erzakova

The aim of this paper is to generalize some fixed point theorems in the class of convex contraction of order $m$ on a complete suprametric space. Then, we will prove that the class of convex contraction of order m is strong enough to…

General Mathematics · Mathematics 2026-05-11 Nicola Fabiano , Sedigheh Barootkoob , Hossein Lakzian

In this paper, we prove new existence and multiplicity results for critical points of lower semicontinuous functionals in Banach spaces, complementing the nonsmooth critical point theory set forth by Szulkin and avoiding the need of the…

Analysis of PDEs · Mathematics 2026-03-11 Jaeyoung Byeon , Norihisa Ikoma , Andrea Malchiodi , Luciano Mari

We establish common fixed point theorems for two pairs of weakly compatible self-mappings using an auxiliary function of two variables. Unlike classical results, our theorems do not assume continuity of the mappings and require completeness…

Functional Analysis · Mathematics 2025-09-10 Babu G. V. R. , Alemayehu Negash , Sandhya M. L. , Meaza Bogale

Another proof that uniformly nonsquare Banach spaces have the fixed point property is presented.

Functional Analysis · Mathematics 2024-03-26 Tim Dalby

We consider a new type of mappings in metric spaces which can be characterized as mappings contracting perimeters of triangles. It is shown that such mappings are continuous. The fixed-point theorem for such mappings is proved and the…

General Topology · Mathematics 2023-08-03 Evgeniy Petrov

We consider maps defined on the interior of a normal, closed cone in a real Banach space that are nonexpansive with respect to Thompson's metric. With mild compactness assumptions, we prove that the Krasnoselskii iterates of such maps…

Functional Analysis · Mathematics 2023-08-15 Brian Lins

An algebra of bounded linear operators on a Banach space is said to be {\em strongly compact} if its unit ball is precompact in the strong operator topology, and a bounded linear operator on a Banach space is said to be {\em strongly…

Functional Analysis · Mathematics 2012-08-17 Miguel Lacruz , Maria del Pilar Romero de la Rosa

In this work, using a new geometrical approach we study to the existence of the fixed-point of mappings that independence of the smoothness, and also of their single-values or multi-values. This work proved the theorems that generalize in…

Analysis of PDEs · Mathematics 2022-03-22 Kamal N. Soltanov

The aim of this paper is to present some fixed point theorems for generalized contractions by altering distance functions in a complete cone metric spaces endowed with a partial order. We also generalize fixed point theorems of J. Harjani,…

Functional Analysis · Mathematics 2012-05-31 Mehdi Asadi , Hossein Soleimani

In the present paper, we prove generalizations of Banach, Kannan, Chatterjea, \'Ciri\'c-Reich-Rus fixed point theorems, as well as of the fixed point theorem for mappings contracting perimeters of triangles. We consider corresponding…

General Topology · Mathematics 2025-01-10 Evgeniy Petrov , Ruslan Salimov , Ravindra K. Bisht