Timeline for Derivative is Zero on a dense G_delta set
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
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| Nov 29, 2016 at 22:22 | comment | added | Pietro Majer | @R if you read more carefully, $g(x)$ is the inverse of a function $f$ with finite derivative at every point, and $f'(x)=0$ iff $g'(f(x))=+\infty$. Of course "derivative" here has the usual meaning of limit of the incremental ratio in the extended real line. Quite a nice and well-written article, indeed. | |
| Nov 29, 2016 at 16:56 | comment | added | Cameron Zwarich | The function they actually take in the end is the inverse of that one, which has finite derivative everywhere. | |
| Nov 29, 2016 at 16:35 | comment | added | R.. GitHub STOP HELPING ICE | The WP article is sloppy; it says the derivative at some points "$=+\infty$" and papers over what that means. Maybe there are senses in which it makes sense to call this everywhere-differentiable anyway, but I would call it ae-differentiable. | |
| Nov 29, 2016 at 16:32 | comment | added | Cameron Zwarich | @R.. The first sentence of the link says that it's a derivative of an everywhere differentiable function. | |
| Nov 29, 2016 at 16:30 | comment | added | R.. GitHub STOP HELPING ICE | This function is not however differentiable everywhere, contrary to the assumption in the question. I suspect the question was just misstated though since it doesn't seem to be interesting if you assume that. | |
| Nov 29, 2016 at 12:17 | vote | accept | Neslihan | ||
| Nov 29, 2016 at 12:12 | history | answered | Cameron Zwarich | CC BY-SA 3.0 |