Epigraph
= Epigraph
{title2=$\operatorname{epi}E$}
{wiki=Epigraph_(mathematics)}
The <epigraph> is $\{(u,t):E(u)\leq t\}$. It is a <convex set> exactly when $E$ is a <convex function>, and is a <sequentially closed set> in the <product topology> exactly when $E$ is <sequentially lower semicontinuous>.