T. Kappeler

activity

20032021

most citedOn the extension of the frequency maps of the KdV and the KdV2 equations

23 citations · 242 across the 47 of their papers we have counts for

collaborators

Showing 2018 · math.APShow all

2 papers · 2 filters

math.AP2018

On the non-existence of local Birkhoff coordinates for the focusing NLS equation

T. Kappeler, P. Topalov

We prove that there exist potentials so that near them the focusing non-linear Schrödinger equation does not admit local Birkhoff coordinates. The proof is based on the constructio…

math.AP2018

On the $L^{p}$ norm of the torsion unction

Michiel van den Berg, Thomas Kappeler

Bounds are obtained for the $L^{p}$ norm of the torsion function $v_{Ω}$ , i.e. the solution of $- Δ v = 1, v \in H_{0}^{1} (Ω),$ in terms of the Lebesgue measure of $Ω$ and the principal eigen…

On the non-existence of local Birkhoff coordinates for the focusing NLS equation

On the Lp norm of the torsion unction

On the $L^{p}$ norm of the torsion unction