{ "id": "1707.01843", "version": "v1", "published": "2017-07-06T15:52:11.000Z", "updated": "2017-07-06T15:52:11.000Z", "title": "Non-escaping endpoints do not explode", "authors": [ "Vasiliki Evdoridou", "Lasse Rempe-Gillen" ], "comment": "18 pages, 2 figures", "categories": [ "math.DS", "math.CV" ], "abstract": "The family of exponential maps $f_a(z)= e^z+a$ is of fundamental importance in the study of transcendental dynamics. Here we consider the topological structure of certain subsets of the Julia set $J(f_a)$. When $a\\in (-\\infty,-1)$, and more generally when $a$ belongs to the Fatou set of $f_a$, it is known that $J(f_a)$ can be written as a union of \"hairs\" and \"endpoints\" of these hairs. Alhabib and the second author, extending a result of Mayer, recently proved that, while the set of endpoints is totally separated, its union with infinity is a connected set. In fact this is true even for the smaller set of all escaping endpoints. We show that, in contrast, the set of non-escaping endpoints together with infinity is totally separated. It turns out that this property is closely related to a topological structure known as a \"spider's web\"; in particular we give a new topological characterisation of spiders' webs that may be of independent interest. We also show how our results can be applied to Fatou's function, $z\\mapsto z + 1 + e^{-z}$.", "revisions": [ { "version": "v1", "updated": "2017-07-06T15:52:11.000Z" } ], "analyses": { "subjects": [ "37F10", "30D05", "54G15" ], "keywords": [ "non-escaping endpoints", "topological structure", "spiders web", "fundamental importance", "smaller set" ], "note": { "typesetting": "TeX", "pages": 18, "language": "en", "license": "arXiv", "status": "editable" } } }