Timeline for Norm of commutators (bis)
Current License: CC BY-SA 2.5
10 events
| when toggle format | what | by | license | comment | |
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| Apr 13, 2017 at 12:58 | history | edited | CommunityBot |
replaced http://mathoverflow.net/ with https://mathoverflow.net/
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| Nov 3, 2010 at 20:53 | vote | accept | Denis Serre | ||
| Nov 3, 2010 at 19:55 | answer | added | user6976 | timeline score: 6 | |
| Nov 3, 2010 at 18:42 | comment | added | user6976 | @Denis: Thanks for the question. I did not know this characterization of nilpotent matrices. | |
| Nov 3, 2010 at 15:51 | comment | added | Denis Serre | When $a_{ij}=0$ for every pair such that $j-i\ne1$, we may take $B$ diagonal, in such a way that $\|B\|_2=\frac{n-1}{2}$ and $\|B\|_F=\sqrt{n\frac{n^2-1}{12}}$. | |
| Nov 3, 2010 at 15:33 | history | edited | Denis Serre | CC BY-SA 2.5 |
partial answer
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| Nov 3, 2010 at 14:55 | comment | added | Denis Serre | @Mark. First of all, I edited my question, because obviously an inequality like $\|B\|\le \mu\|A\|$ cannot hold true. Because the best $B$ is homogeneous of degree zero as a function of $A$. | |
| Nov 3, 2010 at 14:53 | history | edited | Denis Serre | CC BY-SA 2.5 |
added 39 characters in body
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| Nov 3, 2010 at 14:41 | comment | added | user6976 | What is $\mu(2)$? Nilpotent matrices there are easy to describe. | |
| Nov 3, 2010 at 14:18 | history | asked | Denis Serre | CC BY-SA 2.5 |