Über offene Abbildungen auf die 3-Sphäre.
Uniform weight of uniform quotients
Uniforme Räume mit einer linear geordneten Basis.
Universal images of universal elements
We furnish several necessary and sufficient conditions for the following property: For a topological space X, a continuous selfmapping S of X and a family τ of continuous selfmappings of X, the image under S of every τ-universal element is also τ-universal. An application in operator theory, where we extend results of Bourdon, Herrero, Bes, Herzog and Lemmert, is given. In particular, it is proved that every hypercyclic operator on a real or complex Banach space has a dense invariant linear manifold...
Universal mappings and weakly confluent mappings
Upper semicontinuous decompositions of spaces having bases of countable order