Timeline for Root systems and sums of squares
Current License: CC BY-SA 3.0
3 events
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| Apr 13, 2017 at 12:57 | history | edited | CommunityBot |
replaced http://mathoverflow.net/ with https://mathoverflow.net/
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| May 31, 2015 at 6:10 | comment | added | WKC | I just came across this question. It was Mordell who proved that $E_6$ is not represented by any sum of squares. See "The representation of a definite quadratic form as a sum of two others’, Ann. Math. 38 (1937), 751–757. | |
| Jan 19, 2014 at 4:20 | history | answered | Noam D. Elkies | CC BY-SA 3.0 |