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Given a contraction of a variety X to a base Y, we enhance the locus in Y over which the contraction is not an isomorphism with a certain sheaf of noncommutative rings D, under mild assumptions which hold in the case of (1) crepant partial…

Algebraic Geometry · Mathematics 2018-11-28 Will Donovan , Michael Wemyss

The paper is the last in the cycle devoted to the solution of Alexandrov's problem for non-positively curved spaces. Here we study non-positively curved spaces in the sense of Busemann. We prove that if $X$ is geodesically complete…

Metric Geometry · Mathematics 2008-05-13 P. D. Andreev

Several mathematicians, including myself, have studied some unifications in general topological spaces as well as in fuzzy topological spaces. For instance in our earlier works, using operations on topological spaces, we have tried to unify…

General Topology · Mathematics 2008-02-08 T. Hatice Yalvac

Let $X$ be a set and $2^X$ be a set of all subsets of $X$. The necessary and sufficient conditions under which a mapping $X \to 2^X$ is a closure of one-point sets in some $T_0$-space $(X, \tau)$ are described. It is proved that every…

General Topology · Mathematics 2025-12-02 Oleksiy Dovgoshey , Ruslan Shanin

There are several compactification procedures in topology, but there is only one standard discretization, namely, replacing the original topology with the discrete topology. We give a notion of discretization which is dual (in categorical…

General Topology · Mathematics 2014-12-16 Massoud Amini , Nasser Golestani

A topological space is nonseparably connected if it is connected but all of its connected separable subspaces are singletons. We show that each connected first countable space is the image of a nonseparably connected complete metric space…

Metric Geometry · Mathematics 2009-11-05 T. Banakh , M. Vovk , M. R. Wójcik

We investigate two approximation relations on a T0 topological space, the n-approximation, and the d-approximation, which are generalizations of the way-below relation on a dcpo. Different kinds of continuous spaces are defined by the two…

General Topology · Mathematics 2022-07-08 Yuxu Chen , Hui Kou , Zhenchao Lyu

A linkage is a finite graph with lengths assigned to each edge. A planar realization is a map to the plane which preserves edge lengths. It can be thought of as a mechanical device formed from stiff rods and rotating joints. We look at the…

Algebraic Geometry · Mathematics 2007-05-23 Henry C. King

In a spherically complete ultrametric space, a strictly contracting mapping has a fixed point. We indicate in this paper how this fixed point can either be reached or approximated.

Metric Geometry · Mathematics 2013-07-25 Sibylla Priess-Crampe , Paulo Ribenboim

We shall generalize the concept of $z=(1-t)x\oplus ty$ to $n$ times which contains to verifying some their properties and inequalities in CAT(0) spaces. In the sequel with introducing of $\alpha$-nonexpansive mappings, we obtain some fixed…

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

When finding an original proof to a known result describing expansive mappings on compact metric spaces as surjective isometries, we reveal that relaxing the condition of compactness to total boundedness preserves the isometry property and…

Functional Analysis · Mathematics 2019-10-24 Marat V. Markin , Edward S. Sichel

We investigate harmonic maps from weighted graphs into metric spaces that locally admit unique centers of gravity, like Alexandrov spaces with upper curvature bounds. We prove an existence result by constructing an iterative geometric…

Metric Geometry · Mathematics 2007-08-22 J. Jost , L. Todjihounde

Ellis's "functional approach" allows one to obtain proper compactifications of a topological group $G$ if $G$ can be represented as a subgroup of the homeomorphism group of a space $X$ in the topology of pointwise convergence and $G$-space…

General Topology · Mathematics 2025-11-24 K. L. Kozlov , B. V. Sorin

We investigate the relationship between the compactness of embeddings of Sobolev spaces built upon rearrangement-invariant spaces into rearrangement-invariant spaces endowed with $d$-Ahlfors measures under certain restriction on the speed…

Functional Analysis · Mathematics 2022-05-16 Jan Lang , Zdeněk Mihula , Luboš Pick

We give a definition of a functor compactifying the functor of bundles on a surfaces. Earlier different authors have defined similar spaces as either images under a morphism or a quotient by an equivalence relation. We use the technique of…

Algebraic Geometry · Mathematics 2015-02-12 Vladimir Baranovsky

We prove that a meromorphic map defined on the complement of a compact subset of a three-dimensional Stein manifold M and with values in a compact complex three-fold X extends to the complement of a finite set of points. If X is simply…

Complex Variables · Mathematics 2007-05-23 Sergei Ivashkovich , Bernard Shiffman

A smooth compactification X<n> of the configuration space of n distinct labeled points in a smooth algebraic variety X is constructed by a natural sequence of blowups, with the full symmetry of the permutation group S_n manifest at each…

Algebraic Geometry · Mathematics 2007-05-23 Alexander Ulyanov

Finite topological spaces became much more essential in topology, with the development of computer science. The task of this paper is to study and investigate some properties of such spaces with the existence of an ordered relation between…

General Topology · Mathematics 2007-05-23 A. El-Fattah El-Atik , M. E. Abd El-Monsef , E. I. Lashin

A finite relational structure A is called compact if for any infinite relational structure B of the same type, the existence of a homomorphism from B to A is equivalent to the existence of homomorphisms from all finite substructures of B to…

Logic · Mathematics 2026-03-09 Claude Tardif

An old question of A.V. Arhangel'skii asks if the Menger property of a Tychonoff space $X$ is preserved by homeomorphisms of its function space $C_p(X)$. We provide affirmative answer in the case of linear homeomorphisms. To this end, we…

General Topology · Mathematics 2023-11-27 Mikołaj Krupski