* The empty polytope. No vertices and rays.
H-representation
begin
   13   7   integer
 0  1  0  0  0  0  0
 0  0  1  0  0  0  0
 0  0  0  1  0  0  0
 0  0  0  0  1  0  0
 0  0  0  0  0  1  0
 0  0  0  0  0  0  1
 1 -1  0  0  0  0  0
 1  0 -1  0  0  0  0
 1  0  0 -1  0  0  0
 1  0  0  0 -1  0  0
 1  0  0  0  0 -1  0
 1  0  0  0  0  0  -1
 -2 1  0  0  0  0   0
end