Bombieri's Inequality

For Homogeneous Polynomials $P$ and $Q$ of degree $m$ and $n$, then

$$[P\cdot Q]_2 \geq \sqrt{m!n!\over (m+n)!}\, [P]_2[Q]_2,$$

where $[P\cdot Q]_2$ is the Bombieri Norm. If $m=n$, this becomes

$$[P\cdot Q]_2 \geq [P]_2[Q]_2.$$

See also Beauzamy and Dégot's Identity, Reznik's Identity