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Timeline for property of convex functions

Current License: CC BY-SA 3.0

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Sep 19, 2017 at 18:16 history edited Hammerhead CC BY-SA 3.0
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Sep 7, 2017 at 4:59 vote accept Hammerhead
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Sep 7, 2017 at 4:55 vote accept Hammerhead
Sep 7, 2017 at 4:59
Sep 6, 2017 at 3:16 answer added fedja timeline score: 10
S Aug 31, 2017 at 16:48 history bounty started Hammerhead
S Aug 31, 2017 at 16:48 history notice added Hammerhead Draw attention
Aug 25, 2017 at 19:27 history edited Hammerhead CC BY-SA 3.0
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Aug 23, 2017 at 15:53 history edited Hammerhead CC BY-SA 3.0
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Aug 23, 2017 at 5:23 history edited Hammerhead CC BY-SA 3.0
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Aug 23, 2017 at 5:23 comment added Hammerhead Indeed, Fan. It is better to assume that (edited). Though otherwise, $P$ would have to be contained in a lower dimensional hyperplane, in which case we could just take a lower dimensional integral.
Aug 23, 2017 at 5:14 comment added Fan Zheng Probably you want $P$ to be open (or at least has positive measure). Otherwise when $P$ is a segment in $\mathbb R^2$ the left bound cannot hold.
Aug 23, 2017 at 2:48 history edited Hammerhead CC BY-SA 3.0
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Aug 23, 2017 at 1:55 comment added Hammerhead Fedja, indeed $A$ and $B$ can be take to be zero. Thanks for pointing that out, I edited the question. I was blinded with the particular application of this inequality that interests me, and that naturally involves the constants $A,B$. Anyway, If you know a 5 line proof for the first inequality please share it with us. My argument is more convoluted, that is why I am (still) interested in a reference.
Aug 23, 2017 at 1:47 history edited Hammerhead CC BY-SA 3.0
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Aug 22, 2017 at 22:32 comment added fedja It is one of those situations where sending the reader to the library wastes more of his time than writing a 5-line proof, so I would advise not to bother about any references here though the choice is yours. Still I'm unable to understand what $A$ and $B$ are doing in a completely homogeneous problem.
Aug 22, 2017 at 7:43 comment added Kavi Rama Murthy The right-hand inequality does not even require convexity of P or f provided P is bounded and f is continuous.: let g=max{f,0} and h=-min{f.0}. Then the right-hand inequality follows from the fact that 2$\int g$ $\leq$ 2(sup g) m(P)=2(sup f) m(P) by changing f to -f. Note that sup f $\geq$ 0 by the hypothesis (unless f is 0).
Aug 21, 2017 at 22:15 comment added Yoav Kallus @GeraldEdgar I think you missed that $\alpha,\beta,A,B>0$.
Aug 21, 2017 at 21:41 history asked Hammerhead CC BY-SA 3.0