Goal:
  
  G1 : t
  G2 : t
  l : labelling
  Gl := relabel_on G1 G2 l : t
  H : invariants G1
  preserves_edges : forall e : EdgeSet.elt,
                    EdgeSet.In e (E G1) -> EdgeSet.In e (E G2)
  HGl : correct_labelling G1 l
  H0 : invariants G2
  H1 : acyclic_no_loop G2
  embed : forall v1 v2 : VSet.elt,
          VSet.In v1 (V G1) ->
          VSet.In v2 (V G1) -> (lsp G2 v1 v2 <= lsp G1 v1 v2)%nbar
  x : V.t
  s : VSet.t
  p : SPath Gl s x x
  y : VSet.elt
  yinp : VSet.In y (snodes Gl p)
  yin1 : VSet.In y (V G1)
  q : SPath Gl s y y
  wq : sweight q = sweight p
  _x_ : Z
  wp : sweight p > 0
  b : sweight p <= 0 + (Z.of_nat (l y) - Z.of_nat (l y))
  cstr : 0 <= Z.of_nat (l y)
  ============================
   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