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Apr 13, 2017 at 12:19 history edited CommunityBot
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Sep 20, 2012 at 8:49 vote accept Alekk
Sep 20, 2012 at 1:40 answer added George Lowther timeline score: 5
Sep 18, 2012 at 19:51 comment added Alekk @George: great! I can't believe that I missed that. I did notice that the whole thing was invariant by rearrangement but did not see that $E \|X\|^d$ was decreasing. Many thanks!
Sep 18, 2012 at 18:56 comment added Mark Meckes @George: very nice! I'm kicking myself for not thinking of it. @Alekk: the buzzwords for what George is describing are "symmetric decreasing rearrangement". See Chapter 3 of Analysis by Lieb and Loss for more information.
Sep 18, 2012 at 18:36 comment added George Lowther The answer must be no, and in fact you must have the integral bounded by the volume of a ball of radius $\lVert X\lVert_d$. This is because you can swap regions of equal volume in $R^d$ about to move the large probability regions closer to the origin, which doesn't change the integral but can only decrease $\lVert X\lVert_d$. So, it reduces to the radially decreasing density case.
Sep 18, 2012 at 18:18 answer added Arthur B timeline score: 0
Sep 18, 2012 at 17:54 answer added Mark Meckes timeline score: 2
Sep 18, 2012 at 13:52 history asked Alekk CC BY-SA 3.0