A Siegel disc is a simply connected periodic Fatou component on which the first-return map is holomorphically conjugate to an irrational rotation of the unit disc: , with . Its return iterates are normal because any sequence of rotation factors has a convergent subsequence in the unit circle, giving locally uniform limits after conjugation. The iterates generally do not converge to a constant. This is a rotation domain, illustrating stability without attraction.
Articles by others on the same topic
A Siegel disc is a concept in complex dynamics, a branch of mathematics that studies the behavior of iterated functions in the complex plane. It is associated with the dynamics of certain types of complex functions, particularly polynomial maps.