Zobrazeno 1 - 10
of 13
pro vyhledávání: '"Poeschel, Jürgen"'
Autor:
Pöschel, Jürgen
We consider the KAM theory for rotational flows on an $n$-dimensional torus. We show that if its frequencies are diophantine of type $n-1$, then Moser's KAM theory with parameters applies to small perturbations of weaker regularity than $C^n$. Deriva
Externí odkaz:
http://arxiv.org/abs/2104.01866
Autor:
Pöschel, Jürgen
We establish a general version of the Siegel-Sternberg linearization theorem for ultradiffentiable maps which includes the analytic case, the smooth case and the Gevrey case. It may regarded as a small divisior theorem without small divisor condition
Externí odkaz:
http://arxiv.org/abs/1702.03691
Autor:
Pöschel, Jürgen
We give complete and exact descriptions of spaces of ultradifferentiable functions that are closed under composition with either holomorphic or ultradifferentiable functions -- which are two distinct cases. The proof works by considering formal power
Externí odkaz:
http://arxiv.org/abs/1605.07528
Autor:
Pöschel, Jürgen
Recently R\"ussmann proposed a new new variant of KAM theory based on a slowly converging iteration scheme. It is the purpose of this note to make this scheme accessible in an even simpler setting, namely for analytic perturbations of constant vector
Externí odkaz:
http://arxiv.org/abs/0909.1015
Autor:
Pöschel, Jürgen
Publikováno v:
Proceedings of Symposia in Pure Mathematics 69, 2001, 707--732
The purpose of this lecture is to describe the KAM theorem in its most basic form and to give a complete and detailed proof. This proof essentially follows the traditional lines laid out by the inventors of this theory, and the emphasis is more on th
Externí odkaz:
http://arxiv.org/abs/0908.2234
Autor:
Pöschel, Jürgen
We describe a new, short proof of some facts relating the gap lengths of the spectrum of a potential of Hill's equation to its regularity. For example, a real potential is in a weighted Gevrey-Sobolev space if and only if its gap lengths belong to a
Externí odkaz:
http://arxiv.org/abs/0908.0491
We consider the nonlinear Schrodinger equation with a cubic nonlinearity on the circle, which is known to represent an integrable Hamiltonian system. We construct a global coordinate systems, which puts this Hamiltonian into standard normal form, so
Externí odkaz:
http://arxiv.org/abs/0907.3938
Autor:
Kappeler, Thomas *, Pöschel, Jürgen
Publikováno v:
In Annales de l'Institut Henri Poincaré / Analyse non linéaire May-June 2009 26(3):841-853
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