Goal:
    x : VSet.elt  p : VSet.t  H : ~ VSet.In x p
  ============================
   (VSetDecide.MSetDecideAuxiliary.MSet_Prop (~ VSet.In x p))


DEBUG:Going to execute:
t
DEBUG LTAC Evaluated term: (VSetDecide.MSetDecideAuxiliary.MSet_Prop
                              (~ VSet.In x p))