skeleton -- computes the k-skeleton of a Fan

i1 : P = convexHull matrix{{1,0,0,0},{0,1,0,0},{0,0,1,0}}

o1 = {ambient dimension => 3           }
      dimension of lineality space => 0
      dimension of polyhedron => 3
      number of facets => 4
      number of rays => 0
      number of vertices => 4

o1 : Polyhedron

i2 : F = normalFan P

o2 = {ambient dimension => 3         }
      number of generating cones => 4
      number of rays => 4
      top dimension of the cones => 3

o2 : Fan

i3 : F1 = skeleton(2,F)

o3 = {ambient dimension => 3         }
      number of generating cones => 6
      number of rays => 4
      top dimension of the cones => 2

o3 : Fan

i4 : apply(genCones F1,rays)

o4 = {| 0 0 |, | 1 0 |, | 1 -1 |, | -1 0 |, | 0 -1 |, | 1 0 |}
      | 1 0 |  | 0 1 |  | 0 -1 |  | -1 0 |  | 1 -1 |  | 0 0 |
      | 0 1 |  | 0 0 |  | 0 -1 |  | -1 1 |  | 0 -1 |  | 0 1 |

o4 : List