Goal:
  
  x : V.t
  s0 : VSet.t
  s1 : VSet.t
  s2 : VSet.t
  disjadd : DisjointAdd x s1 s2
  disj20 : Disjoint s2 s0
  disj0' : Disjoint s1 s0
  _a_ : VSet.elt
  ins0 : VSet.In _a_ s1
  ============================
   (VSet.E.eq _a_ x -> False)


DEBUG:Going to execute:
move  =>eq; rewrite eq in   ins0
DEBUG LTAC Evaluated term: VSet.inter_spec
DEBUG LTAC Evaluated term: (iffLR
                              (Q:=VSet.In _a_ s1 /\
                                  VSet.In _a_ (VSet.add x s0))
                              (VSet.inter_spec s1 (VSet.add x s0) _a_)
                              _view_subject_)
DEBUG LTAC Evaluated term: VSet.add_spec
DEBUG LTAC Evaluated term: (iffLR (Q:=VSet.E.eq _a_ x \/ VSet.In _a_ s0)
                              (VSet.add_spec s0 x _a_) _view_subject_)