{ "id": "1408.5015", "version": "v1", "published": "2014-08-21T14:21:12.000Z", "updated": "2014-08-21T14:21:12.000Z", "title": "Uniquely universal sets in $\\mathbb{R} \\times ω$ and $[0,1] \\times ω$", "authors": [ "Alicja Krzeszowiec" ], "categories": [ "math.GN" ], "abstract": "Let $X$ and $Y$ be topological spaces. We say that $X\\times Y$ satisfies the Uniquely Universal property (UU) iff there exists an open set $U\\subseteq X\\times Y$ such that for every open set $W\\subseteq Y$ there is a unique cross section of $U$ with $U\\left( x\\right) =\\left\\{ y\\in Y:\\left( x,y\\right) \\in U\\right\\} =W$. Arnold W. Miller in his paper \\cite{1} posed the following two questions: 1. Does $[ 0,1] \\times \\omega $ have UU? 2. Does $ \\mathbb{R} \\times \\omega $ have UU? In this paper we present two constructions which give positive answers to both problems.", "revisions": [ { "version": "v1", "updated": "2014-08-21T14:21:12.000Z" } ], "analyses": { "keywords": [ "uniquely universal sets", "open set", "unique cross section", "uniquely universal property", "topological spaces" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2014arXiv1408.5015K" } } }