Goal:
  
  s : VSet.t
  s' : VSet.t
  s'' : VSet.t
  da : forall a : V.t, VSet.In a s -> VSet.In a s'
  i : V.t
  disj : ~ VSet.In i (VSet.inter s' s'')
  ininter : VSet.In i (VSet.inter s s'')
  ============================
   (VSet.In i (VSet.inter s' s''))


DEBUG:Going to execute:
cbv beta zeta in *
Level 1: Backtrace:

Cannot find any non-recursive equality over s.
Level 1: Backtrace:

Cannot find any non-recursive equality over s.
Level 0: Backtrace:

Cannot find any non-recursive equality over s.