Please can I ask you to elaborate on this, as I am struggling to conceptualize it?
To me the property of being closed (angles of a triangle add up to more than 180) implies that the topology will wrap back on itself.
Can you give some examples of shapes where this is not the case - closed, but does not wrap back on itself?
Also, I seem to remember Krauss talking about flatness implying that it is infinite in spatial extent (or am I just misunderstanding him again?) - doesn't "infinite in spatial extent" rule out a topology that wraps back on itself?
Yes, I still don't quite have a handle on all this ;-)