Über die Einlagerung topologischer Gruppen in Kompakte
Über die Erzeugung von eigentlichen Transformationsgruppen.
Ueber eine Aufgabe aus der Geometria situs
Ultracompanions of subsets of a group
Let be a group, be the Stone-Čech compactification of endowed with the structure of a right topological semigroup and . Given any subset of and , we define the -companion of , and characterize the subsets with finite and discrete ultracompanions.
Ultrafilter spaces and compactifications.
Ultrafilter-limit points in metric dynamical systems
Given a free ultrafilter on and a space , we say that is the -limit point of a sequence in (in symbols, -) if for every neighborhood of , . By using -limit points from a suitable metric space, we characterize the selective ultrafilters on and the -points of . In this paper, we only consider dynamical systems , where is a compact metric space. For a free ultrafilter on , the function is defined by - for each . These functions are not continuous in general. For a...
Ultrafilters on a discrete set with two binary operations.
Ultraparacompactness in certain Pixley-Roy hyperspaces
Una generalizzazione degli spazi di Fréchet
Una nota sobre espacios paracompactos.
Uncountable Powers of ... can be almost Lindelöf.
Une méthode de construction squelette par squelette dans les espaces paracompacts
Dans cet article, on développe, pour les espaces paracompacts, une méthode de construction analogue à la construction par récurrence sur les squelettes dans les -complexes. On l’applique à des problèmes de prolongement ainsi qu’à l’existence de fonctions canoniques dans les nerfs de recouvrements fermés.
Unification of Some Concepts Similar to the Lindelöf Property
Unified spaces and singular sets for mappings of locally compact spaces
Uniform approximation for sublattices of .
Uniform completeness of topological spaces
Uniform ideal completions
Uniform maps into normed spaces
Thirteen properties of uniform spaces are shown to be equivalent. The most important properties seem to be those related to modules of uniformly continuous mappings into normed spaces, and to partitions of unity.
Uniform normality of topological groups and -groups
Uniformities, Hyperspaces, and Normality.