There is a single closed topological 1-manifold (up to, of course, homeomorphism): $S^1$. The classification of surfaces shows that there are countably many closed topological 2-manifolds. Classification of closed, orientable topological 3-manifolds reveals that there are also a countable number of these, though I am unclear in the non-orientable case. Does every dimension admit only a countable number of closed topological manifolds?
2026-05-05 01:46:47.1777945607
Are there countably many closed manifolds in each dimension?
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Andreas Thom answered this question on MathOverflow here: