Face of a polyhedral cone
= Face of a polyhedral cone
= Faces of a polyhedral cone
{synonym}
A face of a polyhedral cone $C$ is $C\cap\ker\ell$ for a linear functional nonnegative on $C$. Every <convex face> of a polyhedral cone is exposed in this way. Faces include the whole cone and its lineality space, and are closed under intersection.
// Target: geometry-and-topology.bigb