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Jun
20
revised Orientable Surface Covers Non-Orientable Surface
added 4 characters in body
Jun
20
answered Orientable Surface Covers Non-Orientable Surface
Jun
9
revised Embedding covers of manifolds
added adjective
Jun
9
revised Embedding covers of manifolds
added closed examples.
Jun
9
answered Embedding covers of manifolds
Feb
14
reviewed Approve Periodic Function With A Given Functional Equation
Feb
14
revised Mapping Class Group
fixed typo
Jan
26
reviewed Reject Square root of complex number in polar or rectangular form
Jan
26
comment Evaluate the sum $x + \frac{x^3}{3} + \frac{x^5}{5} + … $
What do you get if you set $x = 0$? This kind of checking of special values is useful for quickly detecting mistakes.
Jan
26
answered Why is SO(3) not $S^1 \times S^2$? (Where is the mistake?)
Jan
11
reviewed Approve To find value of a for which series converges
Dec
21
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.