Sobolev inequality (source code)

= Sobolev inequality
{wiki}

A Sobolev inequality bounds a function in one $L^q$ norm by its weak derivatives in another $L^p$ norm. In three dimensions, the first-order case $\|u\|_{L^6}\leq C\|\nabla u\|_{L^2}$ is the endpoint estimate behind the continuous embedding $H^1\hookrightarrow L^6$.