
The author gives a sufficient combinatorial condition for the Julia set of a nonhyperbolic polynomial to be a zero-area Cantor set. In fact, the main result of this paper is that given natural numbers \(m_1,\ldots,m_k\), there are uncountably many combinatorially inequivalent polynomials \(p\) such that the Julia set of \(p\) is a zero-area Cantor set and \(p\) has \(k\) nonescaping critical points \(\omega_1,\ldots,\omega_k\), with respective multiplicities \(m_1,\ldots,m_k\), such that \(\omega_i\) accumulates at \(\omega_j\) for all \(1\leq i,j \leq k\). The engine of the proof is the following theorem [\textit{C. T. McMullen}, Complex dynamics and renormalization, Annals of Mathematics Studies, 135, Princeton,NJ: Univ. Press. (1995; Zbl 0822.30002)]: Let \(U_n\subset \mathbb{C}\) be a sequence of disjoint open sets such that each \(U_n\) is a finite union of disjoint unnested annuli of finite modulus, each component of \(U_{n+1}\) is nested inside a component of \(U_n\) and \(\sum \bmod A_n=\infty\) for any sequence of nested annuli \(A_n\subset U_n\). If \(B_n\) denotes the bounded components of \(\mathbb{C}\setminus U_n\), then \(\bigcap B_n\) is a Cantor set of area zero. The author defines an infinite modulus condition for trees with dynamics, which were introduced in [\textit{R. Pérez-Marco}, Degenerate conformal structures, Manuscript (1999)]. In case such an abstract tree is realized by a polynomial, then its Julia set is contained in the complement of the union of nested sets of disjoint annuli. Thus, by McMullen's theorem, the Julia set is a zero-area Cantor set. Finally, the author shows that every tree with dynamics is realized by a polynomial if it allows certain invariants compatible with the dynamics. Especially, given natural numbers \(m_1,\ldots,m_k\), one can construct a tree with dynamics in such a way that it has the infinite modulus condition, is realized by a polynomial and this polynomial exhibits the properties stated in the main theorem.
complex dynamical systems, polynomials, tree with dynamics, Cantor set, Combinatorics and topology in relation with holomorphic dynamical systems, Julia set, combinatorial condition, Functional equations in the complex plane, iteration and composition of analytic functions of one complex variable, Small divisors, rotation domains and linearization in holomorphic dynamics, Dynamics of complex polynomials, rational maps, entire and meromorphic functions; Fatou and Julia sets
complex dynamical systems, polynomials, tree with dynamics, Cantor set, Combinatorics and topology in relation with holomorphic dynamical systems, Julia set, combinatorial condition, Functional equations in the complex plane, iteration and composition of analytic functions of one complex variable, Small divisors, rotation domains and linearization in holomorphic dynamics, Dynamics of complex polynomials, rational maps, entire and meromorphic functions; Fatou and Julia sets
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