Timeline for Most harmful heuristic?
Current License: CC BY-SA 2.5
10 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 6, 2017 at 5:13 | comment | added | Michael Cotton | The idea that continuity means no jumps and holes and then differentiability means no pointy places or vert ramps is actually pretty useful for students as long as you stress that you're only taking about real functions. | |
| Oct 20, 2016 at 14:37 | comment | added | Neal | @JoeBerner "$1$" certainly doesn't! | |
| Oct 20, 2016 at 13:26 | comment | added | Joe Berner | If $x+1$ is discontinuous because you need to raise the pencil, does it even pass the vertical line test? | |
| Nov 25, 2015 at 19:44 | comment | added | user20948 | @AdrienHardy Sorry, but $x^2\boldsymbol1_{\mathbb Q}(x)$ has no twice derivative at $0$ since it's not differentiable in a neighborhood of $0$. | |
| Feb 15, 2015 at 10:32 | comment | added | Adrien Hardy | Yes, and certainly because of that I remember to be shocked when I realized that a map like $x^2 \boldsymbol{1}_{\mathbb Q}(x)$ is continuous (with all derivatives continuous!) at zero. | |
| Aug 25, 2012 at 19:58 | comment | added | Todd Trimble | Pietro, that's just too funny (albeit in a sad way). For that matter, $x$ is discontinuous, unless you're in the habit of making your $x$'s look like $\alpha$'s. | |
| May 23, 2010 at 22:35 | comment | added | Pietro Majer | Victor: compliments, very good knowledge of Italian -and Italians | |
| May 23, 2010 at 7:06 | comment | added | Victor Protsak | @Pietro: Se non e vero, e ben trovatto! | |
| May 22, 2010 at 16:57 | comment | added | Pietro Majer | oh and I heard of a student claiming that "x+1" is not continuous because you need to raise the pencil at least twice whn you write it. | |
| May 22, 2010 at 14:43 | history | answered | Bruno Stonek | CC BY-SA 2.5 |