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comment Fundamental groups of certain 3-manifolds
Your hyperbolic example is wrong: $b^x = b$ is not allowed in a hyperbolic three-manifold. More generally, "non-periodic" is not enough to ensure hyperbolicity. You also need to rule out the "reducible" case.
Dec
18
reviewed Approve Project Motorola: setting up and solving an equation
Dec
15
awarded  Caucus
Nov
9
reviewed Approve Matrix of a linear operator
Oct
29
answered Question about the first proof in Hatcher's Algebraic Topology
Sep
30
awarded  Explainer
Aug
18
awarded  Yearling
Aug
14
revised Is it possible to build a metal wire sphere whose shadow projects the 2d conformal maps of the Riemann Sphere on a flat wall?
another video
Aug
14
comment Is it possible to build a metal wire sphere whose shadow projects the 2d conformal maps of the Riemann Sphere on a flat wall?
Yes. This is illustrated at minute 2:00 in the following video. youtube.com/watch?v=0z1fIsUNhO4 -- the entire video is really excellent, by the way.
Aug
14
answered Explanation of non-orientability of the Möbius band
Aug
14
comment Explanation of non-orientability of the Möbius band
Which book are you referring to? "An introduction to manifolds"? By Loring Tu? I ask because the discussion of the Mobius band is on page 241, not page 208...
Aug
14
answered Is it possible to build a metal wire sphere whose shadow projects the 2d conformal maps of the Riemann Sphere on a flat wall?
Aug
3
comment Mapping Class Group
I've edited my answer to your second question to be just a reference to the Primer.
Aug
3
revised Mapping Class Group
deleted some of the anwser to give a reference instead.
Aug
2
comment Mapping Class Group
Yes - I meant geometric intersection. I'm not sure why you mention homology here.
Aug
2
answered Mapping Class Group
Aug
2
revised Mapping Class Group
fixed grammar and math typos
May
18
comment Deciding which questions to do in a maths exam
In a university or school exam, you should read the whole test before starting on the problems.
May
17
reviewed Approve Derivative of $\Gamma$ at $1$
May
16
revised Another differential topology lemma
rolled back to a previous revision