Sharp Gagliardo-Nirenberg inequality (source code)

= Sharp Gagliardo-Nirenberg inequality
{c}
{wiki=Gagliardo–Nirenberg_interpolation_inequality}

In two dimensions,
$$
\|u\|_4^4\leq
\frac2{\|Q\|_2^2}\|u\|_2^2\|\nabla u\|_2^2,
$$
and equality holds exactly on the phase, translation, and scaling orbit of the <NLS ground state> $Q$.