Goal:
  
  G : t
  HI : invariants G
  HG : acyclic_no_loop G
  n : Z
  x : V.t
  y : V.t
  Vy : ~ VSet.In y (V G)
  Hle : leq_vertices G n x y
  nneg : n <= 0
  n0 : x <> y
  Hxs : lsp G x (s G) = None
  Vx : ~ VSet.In x (V G)
  e : y = y
  Hy : x <> y
  e0 : x = x
  z1 : Z
  XX : z1 + 1 + n <= 0
  H1 : 0 < - n /\ z1 = - n \/ - n <= 0 /\ z1 = 0
  ============================
   False


DEBUG:Going to execute:
lazymatch Zify.zify_convert_to_euclidean_division_equations_flag
           with
           | true =>
               Zify.zify_internal_to_euclidean_division_equations
           | false => idtac
           end