The Hansen polytope 
of a graph 
on 
vertices is the twisted prism of its stable set polytope 
, the convex hull
of the characteristic vectors of the independent
vertex sets of 
. Explicitly,
 |
It is a centrally symmetric convex polytope of dimension 
. Empty graphs produce
hypercubes, while complete
graphs produce cross polytopes. The Hansen
polytopes of split graphs satisfy Kalai's
3d conjecture (Freij et al. 2013).
