let included a b =
let zas = flatten [] a in
let zbs = flatten [] b in
let zb = zunion zbs in
List.fold_left
(fun acc z ->
if Wp_parameters.Simpl.get () && List.exists (Fol.eq_terms z) zbs
then acc
else Bag.add (p_app M.included [z;zb]) acc)
Bag.empty zas