Goal:
  
  G : t
  HI : invariants G
  HG : acyclic_no_loop G
  y_0 : V.t
  x_0 : V.t
  Vx : VSet.In x_0 (V G)
  Vy : VSet.In y_0 (V G)
  Hxs : lsp G x_0 y_0 = None
  K : Z
  XX : correct_labelling G' (fun x : V.t => to_label (lsp G' (s G') x))
  e : EdgeSet.elt
  He : EdgeSet.In e (E G)
  ============================
   (EdgeSet.In e (E G))


DEBUG:Going to execute:
solve
[ trivial
with eq_true
| reflexivity
| symmetry; trivial
| contradiction
| congruence ]