Katrin Fässler

activity

20172026

most citedIsometric Embeddings into Heisenberg Groups

10 citations · 15 across the 5 of their papers we have counts for

collaborators

9 papers

math.MG2026

On low-dimensional uniform rectifiability in Heisenberg groups - Part 2

Yibo Chen, Katrin Fässler, Kilian Zambanini

Let $1 \leq k \leq n$ . We prove that $k$ -dimensional intrinsic Lipschitz graphs in the Heisenberg group $H^{n}$ satisfy a geometric lemma $\mathrm{GLem}(β_{2,\mathcal{V}_k},p)…

math.CV2022★ 3 cited

Hardy spaces and quasiconformal maps in the Heisenberg group

Tomasz Adamowicz, Katrin Fässler

We define Hardy spaces $H^{p}$ , $0 < p < \infty$ , for quasiconformal mappings on the Korányi unit ball $B$ in the first Heisenberg group $H^{1}$ . Our definition is stated in terms…

math.CA2021

Loomis-Whitney inequalities in Heisenberg groups

Katrin Fässler, Andrea Pinamonti

This note concerns Loomis-Whitney inequalities in Heisenberg groups $H^{n}$ : $∣ K ∣ ≲ j = 1 \prod 2 n ∣ π_{j} (K) ∣^{\frac{n + 1}{n ( 2 n + 1 )}}, K \subset H^{n} .$ …

math.CA2020★ 2 cited

Extensions and corona decompositions of low-dimensional intrinsic Lipschitz graphs in Heisenberg groups

Daniela Di Donato, Katrin Fässler

This note concerns low-dimensional intrinsic Lipschitz graphs, in the sense of Franchi, Serapioni, and Serra Cassano, in the Heisenberg group $H^{n}$ , $n \in N$ . For…

math.CA2019

Vertical versus horizontal Sobolev spaces

Katrin Fässler, Tuomas Orponen

Let $α \geq 0$ , $1 < p < \infty$ , and let $H^{n}$ be the Heisenberg group. Folland in 1975 showed that if $f : H^{n} \to R$ is a function in the hori…

math.CA2019

Dorronsoro's theorem in Heisenberg groups

Katrin Fässler, Tuomas Orponen

A theorem of Dorronsoro from the 1980s quantifies the fact that real-valued Sobolev functions on Euclidean spaces can be approximated by affine functions almost everywhere, and at…

math.GR2018

On the quasi-isometric and bi-Lipschitz classification of 3D Riemannian Lie groups

Katrin Fässler, Enrico Le Donne

This note is concerned with the geometric classification of connected Lie groups of dimension three or less, endowed with left-invariant Riemannian metrics. On the one hand, assemb…

math.MG2018

Metric currents and the Poincaré inequality

Katrin Fässler, Tuomas Orponen

We show that a complete doubling metric space $(X, d, μ)$ supports a weak $1$ -Poincaré inequality if and only if it admits a pencil of curves (PC) joining any pair of points $s,t \in…

math.MG2017★ 10 cited

Isometric Embeddings into Heisenberg Groups

Zoltán M. Balogh, Katrin Fässler, Hernando Sobrino

We study isometric embeddings of a Euclidean space or a Heisenberg group into a higher dimensional Heisenberg group, where both the source and target space are equipped with an arb…