English

Dynamical systems method and a homeomorphism theorem

Functional Analysis 2007-05-23 v1

Abstract

Let FF be a nonlinear map in a real Hilbert space HH. Suppose that supuB(u0,R)\sup_{u\in B(u_0,R)} [F(u)]1m(R)\|[F'(u)]^{-1}\|\leq m(R), where B(u0,R)={u:uu0R}B(u_0,R)=\{u:\|u-u_0\|\leq R\}, R>0R>0 is arbitrary, u0Hu_0\in H is an element. If supR>0Rm(R)=\sup_{R>0}\frac{R}{m(R)}=\infty, then FF is surjective. If [F(u)]1au+b\|[F'(u)]^{-1}\|\leq a\|u\|+b, a0a\geq 0 and b>0b>0 are constants independent of uu, then FF is a homeomorphism of HH onto HH. The last result is known as an Hadamard-type theorem, but we give a new simple proof of it based on the DSM (dynamical systems method).

Keywords

Cite

@article{arxiv.math/0408192,
  title  = {Dynamical systems method and a homeomorphism theorem},
  author = {A. G. Ramm},
  journal= {arXiv preprint arXiv:math/0408192},
  year   = {2007}
}