Skeleton graph

Skeleton graph --- остов выпуклого конуса.

The skeleton graph of the convex cone [math]\displaystyle{ C }[/math] is the graph [math]\displaystyle{ G_{C} }[/math] whose vertices are the extreme rays (a face of dimension 1) of [math]\displaystyle{ C }[/math] and there is an edge between two vertices if they are adjacent on [math]\displaystyle{ C }[/math] (two extreme rays of [math]\displaystyle{ C }[/math] are said to be adjacent on [math]\displaystyle{ C }[/math], if they span a two-dimensional face of [math]\displaystyle{ C }[/math]).

The ridge graph of [math]\displaystyle{ C }[/math] is the graph [math]\displaystyle{ G_{C}^{\ast} }[/math] whose vertices are the facets of [math]\displaystyle{ C }[/math] and there is an edge between two nodes if they are adjacent on [math]\displaystyle{ C }[/math]. So, the ridge graph of a convex cone is the skeleton of its dual.