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Timeline for Inf of Jensen's inequality

Current License: CC BY-SA 3.0

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Feb 25, 2018 at 5:33 vote accept yoshi
Feb 25, 2018 at 5:25 answer added Nate Eldredge timeline score: 7
Feb 25, 2018 at 5:18 comment added yoshi aha! ya got it, add it as answer so I can accept! thx
Feb 25, 2018 at 5:15 comment added Nate Eldredge Jensen's inequality $\int c(f)\,d\mu \ge c(\int f\,d\mu)$ is always equality when $f$ is constant, so you would want $dz/dt$ to be constant to saturate. That means $z(t)$ has to be linear, and since you know the endpoints, you're done. Also useful to know is that when $c$ is strictly convex, a constant (almost everywhere) is the only way to saturate.
Feb 25, 2018 at 5:09 history edited yoshi CC BY-SA 3.0
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Feb 25, 2018 at 5:07 comment added yoshi ya, plugging it in works. maybe i should have asked -- how can I see that's the solution. I tried using a direct method of calculus of variations and was getting mixed up.
Feb 25, 2018 at 3:48 comment added Anthony Quas Just consider the straight line path with constant speed: $z(t)=(1-t)x+ty$.
Feb 25, 2018 at 3:09 history asked yoshi CC BY-SA 3.0