3 citations · 3 across the 5 of their papers we have counts for
9 papers
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.
Continuously differentiable functions on compact sets
Leonhard Frerick, Laurent Loosveldt, Jochen Wengenroth
We consider the space of real-valued continuously differentiable functions on a compact subset of a euclidean space. We characterize the completeness of this space and prove that t…
Extension operators for smooth functions on compact subsets of the reals
Leonhard Frerick, Enrique Jorda, Jochen Wengenroth
We introduce sufficient as well as necessary conditions for a compact set such that there is a continuous linear extension operator from the space of restrictions $C^\infty(K)=…
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…
A new proof for the bornologicity of the space of slowly increasing functions
Julian Larcher, Jochen Wengenroth
A. Grothendieck proved at the end of his thesis that the space of slowly increasing functions and the space of rapidly decreasing distributions are bornological. Grothendieck's pro…
Strongly continuous semigroups on some Fréchet spaces
Leonhrd Frerick, Enrique Jordá, Thomas Kalmes +1
We prove that for a strongly continuous semigroup on the Fréchet space of all scalar sequences, its generator is a continuous linear operator and that the semigroup can be represen…
Whitney extension operators without loss of derivatives
Leonhard Frerick, Enrique Jordá, Jochen Wengenroth
For a compact set, we characterize the existence of a linear extension operator E for the space of Whitney jets without loss of derivatives, that is, E satisfies the best possible…