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 Yearling
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Aug
21
comment flat manifold, curvature and the circle
You are confusing two notions of curvature. There is the geodesic curvature of a circle (which depends on its embedding in the plane) and the Riemannian curvature of the circle (which is intrinsic).
Aug
21
answered Question of maps in Mayer-Vietoris sequence
Aug
18
awarded  Yearling
Jul
15
revised Figure eight knot is not a torus knot
typo
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