4 papers · 1 filter
Effros' theorem on transitive group actions with a glimpse into descriptive set theory
Jochen Wengenroth
The main aim of this note is to prove a version of a celebrated theorem of Effros about transitive group actions in a non-metrizable setting, these parts have been formalized and v…
Series representation in tensor products of Banach spaces
Jochen Wengenroth
We show by a ridiculously simple argument that, for any norm on the tensor product of vector spaces, every element of the completion can be represented as a convergent series of el…
Smirnov-decompositions of vector fields
Alberto Rodríguez-Arenas, Jochen Wengenroth
We give streamlined proofs of theorems of S.\ Smirnov about the decomposition of vector fields of measures into curves.
Diametral dimensions of Frechet spaces
Loic Demeulenaere, Leonhard Frerick, Jochen Wengenroth
The diametral dimension is an important topological invariant in the category of Frechet spaces which has been used, e.g., to distinguish types of Stein manifolds. We introduce var…