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For a $p$-permutation equivalence between two block algebras of finite groups, we introduce new square diagrams that link the $p$-permutation equivalence via the Brauer construction to local equivalences between stabilizers of corresponding…

Representation Theory · Mathematics 2025-12-23 Robert Boltje , John Revere McHugh

We present new criteria on the existence of fixed points that combine some monotonicity assumptions with the classical fixed point index theory. As an illustrative application, we use our theoretical results to prove the existence of…

Classical Analysis and ODEs · Mathematics 2014-12-12 Alberto Cabada , José Ángel Cid , Gennaro Infante

Hyre-Ulam stability of functional equation in single variable is studied in non-triangular metric spaces. We derive it as applications of some fixed point results developed on the said structure. A general version of Baker's theorem is also…

Functional Analysis · Mathematics 2024-05-22 Supriti Laha , Lakshmi Kanta Dey

We prove that every continuous function on a separable infinite-dimensional Hilbert space X can be uniformly approximated by smooth functions with no critical points. This kind of result can be regarded as a sort of very strong approximate…

Differential Geometry · Mathematics 2007-05-23 Daniel Azagra , Manuel Cepedello Boiso

We establish the first common fixed point theorem for commutative set-valued mappings. This may help to generalize common fixed point theorems in single-valued setting to those in set-valued. We also prove the existence of a fixed point in…

Functional Analysis · Mathematics 2018-01-08 Issa Mohamadi

We give an elementary proof of Brouwer's fixed-point theorem. The only mathematical prerequisite is a version of the Bolzano-Weierstrass theorem: a sequence in a compact subset of $n$-dimensional Euclidean space has a convergent subsequence…

General Topology · Mathematics 2018-07-31 Henrik Petri , Mark Voorneveld

In this short paper, we prove fixed point theorems for nonexpansive mappings whose domains are unbounded subsets of Banach spaces. These theorems are generalizations of Penot's result in [Proc. Amer. Math. Soc., 131 (2003), 2371--2377].

Functional Analysis · Mathematics 2007-05-23 Tomonari Suzuki

We prove the following generalisation of Schauder's fixed point conjecture: Let $C_1,...,C_n$ be convex subsets of a Hausdorff topological vector space. Suppose that the $C_i$ are closed in $C=C_1\cup...\cup C_n$. If $f:C\to C$ is a…

Algebraic Topology · Mathematics 2012-01-13 Robert Cauty

In the first part of the article, a new interesting system of difference equations is introduced. It is developed for re-rating purposes in general insurance. A nonlinear transformation $\varphi $ of a d-dimensional $(d \ge 2)$ Euclidean…

Optimization and Control · Mathematics 2016-02-12 Muhamed Borogovac

Under the same assumptions made by Mas-Colell et al. (1995), I develop a short, simple, and complete proof of existence of equilibrium prices based on excess demand functions. The result is obtained by applying the Brouwer fixed point…

Theoretical Economics · Economics 2018-09-25 Simone Tonin

We generalize the classical Bernstein theorem concerning the constructive description of classes of functions uniformly continuous on the real line. The approximation of continuous bounded functions by entire functions of exponential type…

Complex Variables · Mathematics 2008-03-11 Vladimir Andrievskii

We show that the following conditions on a C*-algebra are equivalent: (i) it has the fixed point property for nonexpansive mappings, (ii) the spectrum of every self adjoint element is finite, (iii) it is finite dimensional. We prove that…

Operator Algebras · Mathematics 2009-01-26 S. Dhompongsa , W. Fupinwong , W. Lawton

In this paper, we prove common fixed point results for a self-mappings satisfying an implicit function which is general enough to cover a multitude of known as well as unknown contractions. Our results modify, unify, extend and generalize…

Functional Analysis · Mathematics 2017-01-03 Mohammad Imdad , Rqeeb Gubran , Md Ahmadullah

In this paper, using Kronecker's theorem, we discuss the set of common fixed points of an n-parameter continuous semigroup of mappings. We also discuss convergence theorems to a common fixed point of an n-parameter nonexpansive semigroup.

Functional Analysis · Mathematics 2007-05-23 Tomonari Suzuki

In this paper we prove a combinatorial theorem for finite labellings of trees, and show that it is equivalent to a theorem for finite covers of metric trees and a fixed point theorem on metric trees. We trace how these connections mimic the…

Combinatorics · Mathematics 2013-07-10 Andrew Niedermaier , Douglas Rizzolo , Francis Edward Su

In this paper, we show a series of abstract results on fixed point regularity with respect to a parameter. They are based on a Taylor development taking into account a loss of regularity phenomenon, typically occurring for composition…

Dynamical Systems · Mathematics 2018-04-04 Julien Sedro

In this paper, we prove several generalizations and applications of a fixed point theorem. This theorem is used to prove the existence and uniqueness of solutions of the linear sparse matrix problem considered.

Classical Analysis and ODEs · Mathematics 2015-07-30 Xiaorong Liu

We strengthen the Weierstrass approximation theorem by proving that any real-valued continuous function on an interval $I \subset \mathbb{R}$ can be uniformly approximated by a real-valued polynomial whose only (possibly complex) critical…

Classical Analysis and ODEs · Mathematics 2025-01-07 David L. Bishop

We establish an approximate fixed point result for self-maps on compact convex subsets of Hausdorff topological vector spaces where continuity is not a necessary condition.

Functional Analysis · Mathematics 2009-01-29 Cleon S. Barroso

We prove a generalization of the Poincar\'e-Birkhoff theorem for the open annulus showing that if a homeomorphism satisfies a certain twist condition and the nonwandering set is connected, then there is a fixed point. Our main focus is the…

Dynamical Systems · Mathematics 2007-05-23 David Richeson , Jim Wiseman