{ "id": "1606.04025", "version": "v1", "published": "2016-06-13T16:43:57.000Z", "updated": "2016-06-13T16:43:57.000Z", "title": "Topological properties of function spaces over ordinal spaces", "authors": [ "Saak Gabriyelyan", "Jan Grebik", "Jerzy Kakol", "Lyubomyr Zdomskyy" ], "comment": "5 pages, comments are welcome", "categories": [ "math.GN", "math.FA" ], "abstract": "Motivated by the classical Ascoli theorem, a topological space $X$ is said to be an Ascoli space if any compact subset $\\mathcal K$ of $C_k(Y)$ is evenly continuous. We study the $k_{\\mathbb R}$-property and the Ascoli property of $C_p(\\kappa)$ and $C_k(\\kappa)$ over ordinal spaces $\\kappa=[0,\\kappa)$. We prove that $C_p(\\kappa)$ is always an Ascoli space, while $C_p(\\kappa)$ is a $k_{\\mathbb R}$-space iff the cofinality of $\\kappa$ is countable. In particular, this provides the first $C_p$-example of an Ascoli space which is not a $k_{\\mathbb R}$-space, namely $C_p(\\omega_1)$. We show that $C_k(\\kappa)$ is Ascoli iff $\\mathrm{cf}(\\kappa)$ is countable iff $C_k(\\kappa)$ is metrizable.", "revisions": [ { "version": "v1", "updated": "2016-06-13T16:43:57.000Z" } ], "analyses": { "subjects": [ "54C35", "54F05", "46A08", "54E18" ], "keywords": [ "ordinal spaces", "function spaces", "topological properties", "ascoli space", "ascoli property" ], "note": { "typesetting": "TeX", "pages": 5, "language": "en", "license": "arXiv", "status": "editable" } } }