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seen Jul 22 '11 at 2:52

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awarded  Notable Question
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awarded  Yearling
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awarded  Popular Question
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3
awarded  Good Answer
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awarded  Yearling
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18
answered Show that $\mathbb{R}P^1 \simeq S^1$
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15
awarded  Critic
Feb
15
revised How can I prove that $n^7 - n$ is divisible by $42$ for any integer $n$?
added 51 characters in body; deleted 1 characters in body; added 2 characters in body
Feb
15
answered How can I prove that $n^7 - n$ is divisible by $42$ for any integer $n$?
Feb
15
revised Parametrization of a line
added 1236 characters in body
Feb
15
answered Parametrization of a line
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15
comment Square of a graph
Hi Moron, I am relatively new to this, but it seems to me inappropriate to downvote an answer because they did not include a reference. I can see how you might not upvote it because of that (even if I do not agree with it), but downvoting it means that you are saying: "making a little effort, but not as much as I want (you to make) deserves punishment". In other words, I for one appreciate if someone is taking the trouble to answer but not wanting to spend the time to dig up a reference. If they do it from the kindness of their heart, great, but I cannot expect them to do that.
Dec
28
awarded  Nice Answer
Dec
27
comment Do infinity and zero really exist?
Dear Michel, I see that you rephrased your question and I think it is now free of the seeming arrogance of the first version. Kudos for that. As for the content, at the moment I don't think I can add anything to my answer. I believe the issues you raise are completely understandable, but the way to solve them is to try to understand these concepts. The root of your problem is that you are trying to find mathematical ideas in the real word. Mathematics is abstract. Anything you can see is only an approximation of that. (Or if you want, mathematics provides an "abstractization" of real things.)
Dec
27
accepted Square of a graph
Dec
27
comment Square of a graph
Davis, this is certainly interesting. I suppose one rationale I could think of for the definition TonyK gave (and thanks to Moron for the reference, which makes it reasonable to believe that this is the usual terminology) is that if you think of a graph as a category, so the edges represent maps, then $G^2=G\circ G$ could stand for the composition of those maps. I guess this would actually suggest to make edges for those points that are connected by a path of length $2$ exactly. Then again, what do I know?
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27
awarded  Teacher
Dec
27
answered Do infinity and zero really exist?
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26
asked Square of a graph
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17
asked Second Chern class of a ruled surface