Timeline for $f^3,f^2$ are the cube and quadratic of f respectively and both infinite differentiable on $R$,how to show so is $f$
Current License: CC BY-SA 3.0
5 events
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| Apr 6, 2018 at 12:04 | comment | added | fedja | @IosifPinelis 1) As it was mentioned already, you can always reduce to $r,r+1$ and then there is no difference with $2,3$ (except $1/6$ becomes $\frac 1{r(r+1)}$. 2) In a sense it is published now, since it hangs on MO in a public domain. | |
| Apr 6, 2018 at 4:15 | comment | added | Iosif Pinelis | Very nice use of complex analysis in a real-functions problem! Can this proof be extended to the case when $f^{n_1},\dots,f^{n_k}$ are known to be in $C_N$ for some coprime $n_1,\dots,n_k$? In any case, I think this proof should be published, because of its originality and because of the relaxed smoothness condition. | |
| Apr 5, 2018 at 10:51 | history | edited | fedja | CC BY-SA 3.0 |
corrected some ridiculous LaTeX errors
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| Apr 5, 2018 at 1:11 | history | edited | fedja | CC BY-SA 3.0 |
added 249 characters in body
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| Apr 5, 2018 at 1:02 | history | answered | fedja | CC BY-SA 3.0 |