isCompact tests whether P is compact, i.e. a polytope, by checking if the rays and lineality space matrices are 0.
i1 : P = intersection(matrix{{1,1,1},{0,1,0},{-1,-1,-1},{-1,-1,-1},{0,-1,0},{1,-1,1}},matrix{{2},{1},{2},{2},{1},{2}})
o1 = {ambient dimension => 3 }
dimension of lineality space => 1
dimension of polyhedron => 3
number of facets => 5
number of rays => 0
number of vertices => 5
o1 : Polyhedron