2025/08/04 by Contreras, Manuel D., Díaz-Madrigal, Santiago, Gumenyuk, Pavel
#30C55 #30D05 #37F44 #Complex Variables (math.CV) #Dynamical Systems (math.DS) #FOS: Mathematics
paper · doi:10.48550/arxiv.2508.02809
Let φ:\mathbb D → \mathbb D be a parabolic self-map of the unit disc \mathbb D having zero hyperbolic step. We study holomorphic self-maps of \mathbb D commuting with φ. In particular, we answer a question from Gentili and Vlacci (1994) by proving that ψ\inHol(\mathbb D,\mathbb D) commutes with φ if and only if the two self-maps have the same Denjoy-Wolff point and ψ is a pseudo-iterate of φ in the sense of Cowen. Moreover, we show that the centralizer of φ, i.e. the semigroup \mathcal Z_∀(φ):=\ψ:ψ∘φ=φ∘ψ\ is commutative. We also prove that if φ is univalent, then all elements of \mathcal Z_∀(φ) are univalent as well, and if φ is not univalent, then the identity map is an isolated point of \mathcal Z_∀(φ). The main tool is the machinery of simultaneous linearization, which we develop using holomorphic models for iteration of non-elliptic self-maps originating in works of Cowen and Pommerenke.