25 research outputs found
A sharp growth condition for a fast escaping spider's web
We show that the fast escaping set of a transcendental entire function
has a structure known as a spider's web whenever the maximum modulus of
grows below a certain rate. We give examples of entire functions for which the
fast escaping set is not a spider's web which show that this growth rate is
best possible. By our earlier results, these are the first examples for which
the escaping set has a spider's web structure but the fast escaping set does
not. These results give new insight into a conjecture of Baker and a conjecture
of Eremenko
Entire functions with Julia sets of positive measure
Let f be a transcendental entire function for which the set of critical and
asymptotic values is bounded. The Denjoy-Carleman-Ahlfors theorem implies that
if the set of all z for which |f(z)|>R has N components for some R>0, then the
order of f is at least N/2. More precisely, we have log log M(r,f) > (N/2) log
r - O(1), where M(r,f) denotes the maximum modulus of f. We show that if f does
not grow much faster than this, then the escaping set and the Julia set of f
have positive Lebesgue measure. However, as soon as the order of f exceeds N/2,
this need not be true. The proof requires a sharpened form of an estimate of
Tsuji related to the Denjoy-Carleman-Ahlfors theorem.Comment: 17 page
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Baker domains of meromorphic functions
Let be a transcendental meromorphic function and be an invariant Baker domain of . We obtain a new estimate for the growth of the iterates of in , and we use this estimate to improve an earlier result relating the geometric properties of and the proximity of in to the identity function. We illustrate the latter result by considering transcendental meromorphic functions of the form
f(z) = az + bz^ke^{-z}(1+o(1)) \; \mbox{ as } \Re (z) \rightarrow \infty,
where , and , and we show that these functions have Baker domains which contain an unbounded set of critical points and an unbounded set of critical values
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Dimensions of Julia sets of meromorphic functions with finitely many poles
Let be a transcendental meromorphic function with finitely many poles such that the finite singularities of lie in a bounded set. We show that the Julia set of has Hausdorff dimension strictly greater than one and packing dimension equal to two. The proof for Hausdorff dimension simplifies the earlier argument given for transcendental entire functions
Dimensions of Julia sets of meromorphic functions
We show that for any meromorphic function the Julia set has constant local upper and lower box dimensions, and , respectively, near all points of with at most two
exceptions. Further, the packing dimension of the Julia set is equal to . Using this result we show that, for any transcendental entire function in the class (that is, the class of functions such that the singularities of the inverse function are bounded), both the local upper box dimension and packing dimension of are equal to 2. Our approach is to show that the subset of the Julia set containing those points that escape to infinity as quickly as possible has local upper box dimension equal to 2
Microcomputers and Mathematics
Body cremated. George A. Mason - husbandhttps://stars.library.ucf.edu/cfm-ch-register-vol25/1382/thumbnail.jp