Exponential Taylor domination
Abstract
Let be an analytic function in a disk of radius , and assume that is -valent in , i.e. it takes each value at most times in . We consider its Borel transform which is an entire function, and show that, for any , the valency of the Borel transform in is bounded in terms of . We give examples, showing that our bounds, provide a reasonable envelope for the expected behavior of the valency of . These examples also suggest some natural questions, whose expected answer will strongly sharper our estimates. We present a short overview of some basic results on multi-valent functions, in connection with "Taylor domination", which, for , is a bound of all its Taylor coefficients through the first few of them. Taylor domination is our main technical tool, so we also discuss shortly some recent results in this direction.
Keywords
Cite
@article{arxiv.1909.04918,
title = {Exponential Taylor domination},
author = {Omer Friedland and Gil Goldman and Yosef Yomdin},
journal= {arXiv preprint arXiv:1909.04918},
year = {2019}
}