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seen Dec 11 '12 at 23:45

Jul
2
awarded  Curious
Nov
30
comment Is there a conformal self-map on the upper half-plane that swaps two points?
Oh, right, it may be better to think about this on the unit disk since it and the upper half-plane are isomorphic. I'll see what I can cook up, thanks.
Nov
30
asked Is there a conformal self-map on the upper half-plane that swaps two points?
Nov
18
revised Are all even group actions actions on top spaces homeomorphisms?
added 19 characters in body
Nov
18
awarded  Commentator
Nov
18
revised Are all even group actions actions on top spaces homeomorphisms?
Fixed mistakes with my definition.
Nov
18
comment Are all even group actions actions on top spaces homeomorphisms?
@Neal: That's what I get for typing at night, totally mangeled the definition. Thanks for pointing out my mistakes!
Nov
18
comment Are all even group actions actions on top spaces homeomorphisms?
I mean that there is a homomorphism $\phi: G \to homeo(X)$, i.e., the map $g:X \to X, g(x) = gx$ is a homeomorphism.
Nov
18
comment Are all even group actions actions on top spaces homeomorphisms?
@Neal: Fixed. I forgot to exclude the identity element. Consider R as a topological space, Z as the group with the action zr=z+r. This is an even action. It is clearly a bijection and bicontinuous, and so a homeomorphism of R. In general, one defines an action to be continuous which ensures that it is a homeomorphism. My question is basically, are even actions necessarily continuous? My instructor implied this is true, but I'm at loss to show it (probably missing something obvious).
Nov
18
revised Are all even group actions actions on top spaces homeomorphisms?
added 34 characters in body
Nov
18
asked Are all even group actions actions on top spaces homeomorphisms?
Nov
16
comment Möbius map from circles to lines
I tried the second question using the cross ratio, but it doesn't tell me much, just that the ratio is real (which we already knew). I'm thinking now that I want to prove there is a line that that the four points are symmetric in pairs with respect to. Then if I map that line to the imaginary axis, I'll get symmetric points $\pm a, \pm b$ which I can scale down as appropriate.
Nov
16
accepted Möbius map from circles to lines
Nov
16
comment Möbius map from circles to lines
That's what I did. Before, I tried mapping the imaginary axis to the real axis and $-2 \mapsto \infty$, since this would be the desired configuration, by $4i \mapsto 1, 0 \mapsto 0$. This didn't work, though. Turns out I had to do $4i \mapsto 0, 0 \mapsto 1$, which, I guess, had the same orientation as the original circles.
Nov
16
revised Möbius map from circles to lines
added 158 characters in body
Nov
16
asked Möbius map from circles to lines
Nov
11
revised Alternate form of the Residue theorem?
added 20 characters in body
Nov
10
asked Alternate form of the Residue theorem?
Nov
9
accepted Rewrite a series as a power series?
Nov
9
asked Rewrite a series as a power series?