KnowraTietze extension theoremLinked fromLinked fromThe 5 pages that link to Tietze extension theorem, each with the reason it gives.All 5Related 3Compared with 2Normal spaceRelated: It is a major consequence of normality for extending functions.Separation axiomRelated: Normality is the separation hypothesis that makes this extension result possible.Urysohn's lemmaRelated: Its proof builds extensions from Urysohn functions that separate closed sets.