Justification of the dynamical systems method for global homeomorphism
A. G. Ramm Department of Mathematics, Kansas State University, Manhattan, KS, USA
Аннотация:
The dynamical systems method (DSM) is justified for solving operator equations
$F(u)=f$, where
$F$ is a nonlinear operator in a Hilbert space
$H$. It is assumed that
$F$ is a global homeomorphism of
$H$ onto
$H$, that
$F\in C^1_{loc}$, that is, it has the Fréchet derivative
$F'(u)$ continuous with respect to
$u$, that the operator
$[F'(u)]^{-1}$ exists for all
$u\in H$ and is bounded,
$||[F'(u)]^{-1}||\leq m(u)$, where
$m(u)>0$ depends on
$u$, and is not necessarily uniformly bounded with respect to
$u$. It is proved under these assumptions that the continuous analogue of the Newton's method
\begin{equation}
\dot u=-[F'(u)]^{-1}(F(u)-f),\qquad u(0)=u_0,
\tag{1}
\end{equation}
converges strongly to the solution of the equation
$F(u)=f$ for any
$f\in H$ and any
$u_0\in H$. The global (and even local) existence of the solution to the Cauchy problem
$(1)$ was not established earlier without assuming that
$F'(u)$ is Lipschitz-continuous. The case when
$F$ is not a global homeomorphism but a monotone operator in
$H$ is also considered.
Ключевые слова и фразы:
the dynamical systems method (DSM), surjectivity, global homeomorphisms, monotone operators.
MSC: 47J35 Поступила в редакцию: 19.07.2010
Язык публикации: английский