Timeline for When is a singular point of a variety ($\mathcal{C}^\infty$-) smooth?
Current License: CC BY-SA 3.0
14 events
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| Jan 15, 2017 at 19:24 | history | edited | Qfwfq | CC BY-SA 3.0 |
I'm really sorry to spoil the "pun" in the title, but it occurred to me more than once that -on stumbling upon this question- I got quite confused. So I though a parenthetic remark in the title may avoid confusion also for other readers....
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| Jan 14, 2017 at 20:04 | comment | added | Libli | Why didn't you consider in the first place the curve defined by $y^3 +x^2y-x^2y^2-x^4 = 0$? Doesn't it satisfy the same hyptohesis as your original curve? But the explanation why it is $\mathcal{C}^{\infty}$ manifold is so much easier... ($y^3 +x^2y-x^2y^2-x^4 = (y-x^2)(y^2+x^2)$). | |
| Jan 14, 2017 at 1:05 | answer | added | Scot Adams | timeline score: 3 | |
| Jan 5, 2017 at 23:17 | history | edited | Gro-Tsen | CC BY-SA 3.0 |
fix slight computational error / typo (as per comment by John Sidles)
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| Jan 5, 2017 at 22:28 | answer | added | user73454 | timeline score: 7 | |
| Dec 29, 2016 at 1:43 | comment | added | John Sidles | Thank you for this lovely question-and-answer. There is (as it appears to me) one minor typographic error. Namely, in regard to the second edit, the curve $X$ is in fact the image of $\mathbb{R}$ under $\phi(t)=(t(t^2+2),t^2(t^2+2))$, rather than the expression given for $\phi(t)$ (as can be verified by direct substitution). | |
| Jun 29, 2012 at 12:38 | history | edited | Georges Elencwajg | CC BY-SA 3.0 |
Added Second Edit
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| Jun 1, 2012 at 11:18 | vote | accept | Georges Elencwajg | ||
| Jun 1, 2012 at 6:05 | comment | added | Olivier | This question and the answers are fantastic. MO at its very best. | |
| May 30, 2012 at 17:46 | answer | added | Robert Bryant | timeline score: 53 | |
| May 30, 2012 at 17:16 | comment | added | Martin Brandenburg | +1 for your example: Pictures cannot always be trusted .. | |
| May 30, 2012 at 13:26 | history | edited | Georges Elencwajg | CC BY-SA 3.0 |
Added Edit
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| May 30, 2012 at 12:31 | answer | added | Francesco Polizzi | timeline score: 46 | |
| May 30, 2012 at 11:52 | history | asked | Georges Elencwajg | CC BY-SA 3.0 |