Jarńık and Julia; a Diophantine analysis for parabolic rational maps
Jarńık and Julia; a Diophantine analysis for parabolic rational maps
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发表时间:
2013
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通讯作者:
B. Stratmann;M. Urbanski
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作者:
B. Stratmann;M. Urbanski
In this paper we derive a Diophantine analysis for Julia sets of parabolic rational maps. We generalise two theorems of Dirichlet and Jarnik in number theory to the theory of iterations of these maps. On the basis of these results, we then derive a ‘weak multifractal analysis’ of the conformal measure naturally associated with a parabolic rational map. The results in this paper contribute to a further development of Sullivan’s famous dictionary translating between the theory of Kleinian groups and the theory of rational maps. 1 Statement of main results In this paper we derive a Diophantine analysis for Julia sets J(T ) of parabolic rational maps T : Ĉ → Ĉ . We generalise two classical number theoretical theorems of Dirichlet and Jarnik to the theory of iterations of rational maps. We then show that these results embed in the concept of conformal measures, where they admit a ‘weak multifractal analysis’ of the dimH(J(T )) -conformal measure which is naturally associated with the dynamical system (J(T ), T ) . Also, a combination of the results in this paper with those for Kleinian groups obtained in [10], [19], [22] and [24] adds another interesting chapter to Sullivan’s famous ‘Julia-Klein dictionary’ [25] (see also [14], [23]). Recall that for parabolic rational maps it is well-known that J(T ) = Jr(T )∪Jp(T ) , i.e. the Julia set J(T ) admits a disjoint decomposition into the radial Julia set Jr(T ) and the countable set of pre-parabolic points Jp(T ) := ⋃ ω∈Ω ⋃ n∈N T −n(ω) , where Ω denotes the set of rationally indifferent periodic points ([27], [23]). For each ω ∈ Ω , we fix a standard neighbourhood B(ω, rω) and consider, roughly speaking, all its holomorphic, inverse iterates B(c(ω), rc(ω)) . We call these balls canonical balls (see section 2, for the precise definition). A major aim of this paper will be the fractal analysis of the Jarnik-Julia sets. For ω ∈ Ω and σ > 0 , these sets are ‘ lim sup sets’ which are defined by J ω σ (T ) := ⋂