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
  x : V.t
  k : Z
  p : SPath G (V G) x_0 x
  Hk : sweight p = k
  p' := sto_G' p : SPath G' (V G) x_0 x
  p1 : SPath G (VSet.remove y_0 (V G)) x_0 y_0
  p2 : SPath G (VSet.remove y_0 (V G)) x_0 y_0
  ============================
   (VSet.Subset (V G) (V G))


DEBUG:Going to execute:
reflexivity
Level 0: Backtrace:

Proof is not complete.
Level 0: Backtrace:

Proof is not complete.