|WikiProject Mathematics||(Rated Start-class, Mid-priority)|
Not actually relevant to the page, but does anyone know if there is are similar theorems about when a topological space is homeomorphic to a manifold?
I am pretty sure that that the space is submetrizable means that it contains a metrizable subspace or the space is homeomorphic to such a space, but I couldn't find (by means of quick google search) a reference to back this. Does anyone confirm this? Without defining Submetrizablity we can't go deep into the metrizable problems in my opinion. -- Taku 03:40, 3 March 2007 (UTC)
A space is called submetrizable if it has a weaker metrizable topology. The Sorgenfrey line is an example: the usual topology on R is a weaker and metrizable topology.Hennobrandsma 14:01, 2 June 2007 (UTC)
Most texts, Dugundji being an example, consider normality to be a stronger separation axiom than regularity, not weaker. But then this is normality as , and regularity as . Without some clarification in this article, it isn't clear what Urysohn actually said. Further, this article needs style editing--or is it just me who thinks articles on general topology should avoid sounding flippant? 188.8.131.52 (talk) —Preceding comment was added at 15:14, 3 June 2008 (UTC)
Tychonoff's vs. Urysohn version
Under Tychonoff's assumptions X is in fact normal: second-countable implies Lindelöf, and Lindelöf + regular implies normal (this is Tychonoff's lemma). Tychonoff's contribution (his Lemma) was therefore more general than to just extend Urysohn's Metrization Theorem. — Preceding unsigned comment added by 184.108.40.206 (talk) 20:54, 24 October 2012 (UTC)