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The escape trichotomy for singularly perturbed rational maps. (English) Zbl 1087.37043

Summary: We consider the dynamical behavior of the family of complex rational maps given by \[ F_\lambda(z)=z^n+\frac{\lambda}{z^d} \] with \(n\geq 2\), \(d\geq 1\). Despite the high degree of these maps, there is only one free critical orbit up to symmetry. Also, the point at \(\infty\) is always a superattracting fixed-point. Our goal is to consider what happens when the free critical orbit tends to \(\infty\). We show that there are three very different types of Julia sets that occur in this case. Suppose the free critical orbit enters the immediate basin of attraction of \(\infty\) at iteration \(j\). Then we show: (1) If \(j=1\), the Julia set is a Cantor set; (2) If \(j=2\), the Julia set is a Cantor set of simple closed curves; (3) If \(j>2\), the Julia set is a Sierpinski curve.

MSC:

37F10 Dynamics of complex polynomials, rational maps, entire and meromorphic functions; Fatou and Julia sets
37F50 Small divisors, rotation domains and linearization in holomorphic dynamics
32H50 Iteration of holomorphic maps, fixed points of holomorphic maps and related problems for several complex variables
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