Fixed Points, Semigroups and Rigidity of Holomorphic Mappings
David Shoikhet
Holon Institute of Technology, Holon & The Galilee Research Center for Applied Mathematics,
Karmiel, Israel
Abstract:
There is a long history associated with the problem of iterating of
holomorphic mappings and finding their fixed points with the modern
results of F. Bracci, M. Contreras, S. Diaz - Madrigal, K. Goebel, G. Kohr,
M.Kohr, T. Kuczumow, S. Reich, T. Sugawa and J.-P. Vigue being among the most
important.
Historically, complex dynamics and geometrical function theory have been
intensively developed from the beginning of the twentieth century. They
provide the foundations for broad areas of mathematics. In the last fifty
years the theory of holomorphic mappings on complex spaces has been studied
by many mathematicians with many applications to nonlinear analysis,
functional analysis, differential equations, classical and quantum
mechanics. The laws of dynamics are usually presented as equations of motion
which are written in the abstract form of a dynamical system: $\frac{dx}{dt}
+f(x)=0$, where $x$ is a variable describing the state of the system under
study, and $f$ is a vector-function of $x$. The study of such systems when
$f$ is a monotone or an accretive (generally nonlinear) operator on the
underlying space has recently been the subject of much research by analysts
working on quite a variety of interesting topics, including boundary value
problems, integral equations and evolution problems.
In this talk we give a brief description of the classical statements which
combine the celebrated Julia Theorem of 1920, Carathéodory's
contribution in 1929 and Wolff's boundary version of the Schwarz Lemma of
1926 with their modern interpretations for discrete and continuous
semigroups of hyperbolically nonexpansive mappings in Hilbert spaces. We
also present flow-invariance conditions for holomorphic and hyperbolically
monotone mappings.
Finally, we study the asymptotic behavior of one-parameter continuous
semigroups (flows) of holomorphic mappings. We present angular
characteristics of the flows trajectories at their Denjoy-Wolff points, as
well as at their regular repelling points (whenever they exist). This
enables us by using linearization models in the spirit of functional
Schroeder's and Abel's equations and eigen-value problems for composition
operators to establish new rigidity properties of holomorphic generators
which cover the famous Burns-Krantz Theorem.