
Let \(f : \widehat{\mathbb C} \to \widehat{\mathbb C}\) be a rational map of degree \(d \geq 2\), and denote by \(f^n\) the \(n\)th iterate of \(f\). The Fatou set \(F(f)\) is the maximal open set in which the sequence \((f^n)\) of iterates is a normal family in the sense of Montel, while the complement of \(\mathcal{F}(f)\) in \(\widehat{\mathbb C}\) is the Julia set \(J(f)\). A zero of \(f'\) or a multiple pole of \(f\) is called a critical point of \(f\). A point \(z_0 \in \widehat{\mathbb C}\) is called an eventually periodic point of \(f\) if there are integers \(m \geq 0\) and \(p \geq 1\) such that \(f^{m+p}(z_0)=f^m(z_0)\). If all critical points of \(f\) contained in the Julia set \(J(f)\) are eventually periodic, then \(f\) is called geometrically finite. The Fatou set of such a rational map cannot contain Siegel disks or Herman rings. A perturbation \(f_\varepsilon \to f\) of \(f\) is a family of rational maps \(f_\varepsilon\) of degree \(d\) with \(\varepsilon \in [0,1]\), \(f_0=f\) and \(f_\varepsilon \to f\) as \(\varepsilon \to 0\) uniformly on \(\widehat{\mathbb C}\). If \(f_\varepsilon \to f\) is a perturbation of \(f\), and if for \(\varepsilon \in [0,1]\) there is a homeomorphism \(h_\varepsilon : J(f_\varepsilon) \to J(f)\) with \(h_\varepsilon \circ f_\varepsilon = f \circ h_\varepsilon\) on \(J(f_\varepsilon)\), then \(h_\varepsilon\) is called a topological conjugacy between \(f_\varepsilon\) and \(f\) on their respective Julia sets. If \(h_\varepsilon\) is not a homeomorphism but merely continuous and surjective, then \(h_\varepsilon\) is called a semiconjugacy. The author considers so-called horocyclic perturbations of a geometrically finite rational map \(f\) into another geometrically finite rational map \(f_\varepsilon\) which preserves the critical orbit relations with respect to the Julia set of \(f\). He constructs a semiconjugacy or a topological conjugacy between the dynamics of \(f\) and \(f_\varepsilon\) on their Julia sets. For hyperbolic rational maps, the existence of such conjugacies is well known from results of \textit{R.~Mañé}, \textit{P.~Sad} and \textit{D.~Sullivan} [Ann. Sci. Éc. Norm. Supér., IV. Sér. 16, 193--217 (1983; Zbl 0524.58025)]. But this theory is not applicable here, since geometrically finite rational maps may have parabolic cycles. The results in this paper give a partial answer to a conjecture of \textit{L. R.~Goldberg} and \textit{J.~Milnor} [Ann. Sci. Éc. Norm. Supér., IV. Sér. 26, 51--98 (1993; Zbl 0771.30028)].
Expanding holomorphic maps; hyperbolicity; structural stability of holomorphic dynamical systems, geometrically finite rational map, Julia set, critical point, Small divisors, rotation domains and linearization in holomorphic dynamics, Dynamics of complex polynomials, rational maps, entire and meromorphic functions; Fatou and Julia sets, semiconjugacy
Expanding holomorphic maps; hyperbolicity; structural stability of holomorphic dynamical systems, geometrically finite rational map, Julia set, critical point, Small divisors, rotation domains and linearization in holomorphic dynamics, Dynamics of complex polynomials, rational maps, entire and meromorphic functions; Fatou and Julia sets, semiconjugacy
| selected citations These citations are derived from selected sources. This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 6 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Average | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Average | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Average |
