View source for Siegel disks/Quadratic Siegel disks

=== Boundaries of quadratic Siegel disks ===
The boundary of a quadratic Siegel disk can have any prescribed regularity (Buff and Cheritat, 2007). In particular:

'''Theorem.''' <i>For every <math>n\ ,</math> there are quadratic Siegel disks whose boundary
<ul>
<li> is a Jordan curve not containing the critical point and
<li> is a <math>C^n</math> curve but not a <math>C^{n+1}</math> curve.
</ul>
There are also quadratic Siegel disks whose boundary is a Jordan curve not containing the critical point, yet sufficiently irregular not to be a quasicircle.
</i>