Special Session 126: 

The Amazing Universal Fatou Component

Mark D Comerford
University of Rhode Island
USA
Co-Author(s):    Mark Comerford, Christopher Staniszewski
Abstract:
The possibilities for limit functions on a Fatou component for the iteration of a single polynomial or rational function are well understood and quite restricted. In non-autonomous iteration, where one considers compositions of arbitrary polynomials with suitably bounded degrees and coefficients, one should observe a far greater range of behaviour. We show this is indeed the case and we exhibit a bounded sequence of quadratic polynomials which has a bounded Fatou component on which one obtains as limit functions every member of the classical Schlicht family of normalized univalent functions on the unit disc. The main idea behind this is to make use of dynamics on Siegel discs where high iterates of a single polynomial with a Siegel disc $U$ approximate the identity closely on compact subsets of $U$. Do almost nothing and you can do almost anything!