Variable P : ad.
Variable f : mu_form.
Variable re : rel_env.
Hypothesis f_is_ok : f_ok f.
Hypothesis f_ap_ok : mu_form_ap_ok (var_lu 0 N) f.
Hypothesis f_even : f_P_even P f true.
Hypothesis re_ok : ad_to_be_ok (var_lu 0 N) re.
Definition mf (be : bool_expr) := mu_eval f (re_put re P be).
Definition mfs (n : nat) := fst (be_iter2n mf Zero n).

Lemma mf_fix_ex :
exists m : nat,
m <= two_power N /\ be_eq (be_iter1 mf Zero m) (be_iter1 mf Zero (S m)).