Normal fan of a polytope
= Normal fan of a polytope
The normal cone of a face $F$ of a polytope consists of linear functionals whose minimum is attained on all of $F$. These cones form the inward normal fan, complete in the dual of the polytope's affine span. For a full-dimensional <lattice polytope>, it is a complete rational fan in the full dual space.
// Target: geometry-and-topology.bigb