You need to know: Set of complex numbers, absolute value
of
, limits, function
in complex variable z, its derivative
, polynomials, notation
for
where f is applied n times, bounded subsets of
, path (or curve) connecting points
and
.
Background: A function is called entire if
exists for all
. An entire function f is called transcendental if it is not a polynomial. An escaping set of a transcendental entire function f is the set
. A path-component of
is the set of all
which can be connected by a path
to any fixed
.
The Theorem: On 24th April 2007, Günter Rottenfusser, Johannes Rückert, Lasse Rempe, and Dierk Schleicher submitted to arxiv a paper in which they proved the existence of a transcendental entire function f whose escaping set has only bounded path-components.
Short context: The study of limiting behaviour of sequence for transcendental entire function f goes back to 1926 paper of Fatou. This is an example of dynamical system. In 1989, Eremenko, formalising a question of Fatou, asked whether the escaping set
of any transcendental entire function f has the property that every point
can be joined with
by a curve in
. The Theorem answers this question in negative.
Links: Free arxiv version of the original paper is here, journal version is here.