-
Give a non-discrete #topology on the real numbers (or y'know, whatever) closed under arbitrary *intersections*. Yeah, it won't be T1. (Why?)Permalink On twitter.com
♻️ 1 Retweets Mood +1 🙂
-
A T_1 #topology on the real numbers closed under arbitrary *intersections* is discrete because the arbitrary union of singletons is closed.On twitter.com
-
Let {(x,∞):-∞≤x≤∞}∪{[x,∞):-∞<x<∞} give a T_0 #topology on the real numbers. Then the arbitrary union *or intersection* of open sets is open.Permalink On twitter.com