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Dec 21, 2015 at 20:47 comment added A.S. @Kevin Not anything per se. This shows that Holder's bound $|E(XYZ)|\le (E(|X|^3)E(|Y|^3)E(|Z|^3))^{1/3}$ is tight.
Dec 20, 2015 at 17:13 comment added Kevin P. Costello Modified version of this: Let $\eta_1$ and $\eta_2$ be independent, and set $\eta_3=\eta_1 \eta_2$. The variables are still uncorrelated, but now $E(XYZ)=E(\xi^3)$. Even if $E(\xi^3)$ is finite, it could be anything.
Dec 20, 2015 at 16:49 comment added Serguei Popov Then I don't know. Maybe, play with inequalities like $\frac{1}{3}(|XY|+|YZ|+|XZ|)\geq |XYZ|^{2/3}$?..
Dec 20, 2015 at 16:42 comment added Acapello Ok, and if we also assume that $E(XYZ)$ exist?
Dec 20, 2015 at 16:40 history answered Serguei Popov CC BY-SA 3.0