I’ve changed my user name from Math Geek to Orbifold. This will be announced in my signature for a while, but I thought I’d post this as a courtesy to those people who don’t view signatures by default.
Infrequently Asked Questions:
Q: What the heck is an orbifold?
A: A topological space similar to a manifold, but in which certain well-defined types of singularities are permitted. Orbifolds are a generalization of manifolds, and are similar to but not the same as cone manifolds.
(I’m still going to be a Math Geek, I’m just not advertising it as much.)
Ultrafilter: I’m afraid Orbifold wins. I’ve never even heard of an orbifold (until now anyway), but ultrafilters are fairly standard objects.
Although I imagine someone with more background in applied maths / physics than I do at the moment might tell you differently, as orbifolds seem to have an application to string theory.