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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

To a topological groupoid endowed with an involution, we associate a topological groupoid of fixed points, generalizing the fixed-point subspace of a topological space with involution. We prove that when the topological groupoid with…

Algebraic Geometry · Mathematics 2026-05-13 Emiliano Ambrosi , Olivier de Gaay Fortman

Using an algebraic point of view we present an introduction to the groupoid theory, that is, we give fundamental properties of groupoids as, uniqueness of inverses and properties of the identities, and study subgroupoids, wide subgroupoids…

Group Theory · Mathematics 2020-01-29 Jesús Ávila , Víctor Marín , Héctor Pinedo

The fixed point index of topological fixed point theory is a well studied integer-valued algebraic invariant of a mapping which can be characterized by a small set of axioms. The coincidence index is an extension of the concept to…

General Topology · Mathematics 2007-09-27 P. Christopher Staecker

In the setting of step two Carnot groups, we show a "cone property" for horizontally convex sets. Namely we prove that, given a horizontally convex set $C$, a pair of points $P\in \partial C$ and $Q\in $ int $C$, both belonging to a…

Metric Geometry · Mathematics 2019-02-26 Daniele Morbidelli

We give an explicit classification of translation-invariant, Lorentz-invariant continuous valuations on convex sets. We also classify the Lorentz-invariant even generalized valuations.

Differential Geometry · Mathematics 2013-03-28 Semyon Alesker , Dmitry Faifman

We define basic notions in the category of conic representations of a topological group and prove elementary facts about them. We show that a conic representation determines an ordinary dynamical system of the group together with a…

Dynamical Systems · Mathematics 2019-03-25 Matan Tal

In this paper we consider the set of all bounded subsets of totally ordered Dedekind complete Riesz spaces, equipped with the order topology. We show the existence of bounded linear functions on this set, that are invariant under group…

General Mathematics · Mathematics 2017-01-24 George Chailos

Gromov showed that for fixed, arbitrarily large C, any uniformly C-Lipschitz affine action of a random group in his graph model on a Hilbert space has a fixed point. We announce a theorem stating that more general affine actions of the same…

Group Theory · Mathematics 2017-05-09 Shin Nayatani

Probability monads on categories of topological spaces are classical objects of study in the categorical approach to probability theory, with important applications in the semantics of probabilistic programming languages. We construct a…

Category Theory · Mathematics 2024-12-02 Peter Kristel , Benedikt Peterseim

We extend the definitions and main properties of graded extensions to the category of locally compact groupoids endowed with involutions. We introduce Real \v{C}ech cohomology, which is an equivariant-like cohomology theory suitable for the…

Operator Algebras · Mathematics 2012-02-07 El-kaïoum M. Moutuou

Groupoid cardinality is an invariant of locally finite groupoids which has many of the properties of the cardinality of finite sets, but which takes values in all non-negative real numbers, and accounts for the morphisms of a groupoid.…

Category Theory · Mathematics 2025-05-08 Krista Zehr

An isotopic to the identity map of the $2$-torus, that has zero rotation vector with respect to an invariant ergodic probability measure, has a fixed point by a theorem of Franks. We give a version of this result for nilpotent subgroups of…

Dynamical Systems · Mathematics 2022-03-25 Sebastião Firmo , Javier Ribón

This article presents a deep investigation of fixed points for multivalued weak contractions in cone metric spaces. We extend Berinde weak contraction principles to the multivalued setting in cone metric spaces, developing existence,…

Functional Analysis · Mathematics 2025-08-13 Elvin Rada

We elaborate on the representation theorems of topoi as topoi of discrete actions of various kinds of localic groups and groupoids. We introduce the concept of "proessential point" and use it to give a new characterization of pointed Galois…

Category Theory · Mathematics 2007-05-23 Eduardo J. Dubuc

We study the topos of sets equipped with an action of the monoid of regular $2 \times 2$ matrices over the integers. In particular, we show that the topos-theoretic points are given by the double quotient $\left. GL_2(\hat{\mathbb{Z}})…

Algebraic Geometry · Mathematics 2019-08-07 Jens Hemelaer

We obtain new results on the existence and multiplicity of fixed points of Hammerstein equations in very general cones. In order to achieve this, we combine a new formulation of cones in terms of continuous functionals with fixed point…

Classical Analysis and ODEs · Mathematics 2016-11-09 Rubén Figueroa , F. Adrián F. Tojo

For $\mathrm{O}(\mathrm{q},k)$, the orthogonal group over a field $k$ of characteristic 2 with respect to a quadratic form $\mathrm{q}$, we discuss the isomorphism classes of fixed points of involutions. When the quadratic space is either…

Group Theory · Mathematics 2023-01-18 Mark Hunnell , John Hutchens

The concept of convex compactness, weaker than the classical notion of compactness, is introduced and discussed. It is shown that a large class of convex subsets of topological vector spaces shares this property and that is can be used in…

Functional Analysis · Mathematics 2010-06-02 Gordan Zitkovic

We prove fixed point theorems in a space with a distance function that takes values in a partially ordered monoid. On the one hand, such an approach allows one to generalize some fixed point theorems in a broad class of spaces, including…

Functional Analysis · Mathematics 2026-03-24 Vladyslav Babenko , Vira Babenko , Oleg Kovalenko