Goal:
  
  G : t
  s0 : VSet.t
  s' : VSet.t
  x : V.t
  y : V.t
  z : V.t
  p : SPath s0 x y
  t0 : VSet.t
  ============================
   (VSet.Subset s' (VSet.union t0 s'))


DEBUG:Going to execute:
tryif prop (VSetDecide.MSetDecideAuxiliary.MSet_Prop P) holds by
            auto  100 with MSet_Prop then fail else clear H 
Level 1: Backtrace:

t0 is used in conclusion.
Level 1: Backtrace:

t0 is used in conclusion.
Level 1: Backtrace:

t0 is used in conclusion.