Definition bool_fun_var (x : BDDvar) : bool_fun :=
fun vb : var_binding => vb x.

Lemma BDDvar_make_is_var :
forall (cfg : BDDconfig) (x : BDDvar),
BDDconfig_OK cfg ->
bool_fun_eq
(bool_fun_of_BDD (fst (BDDvar_make cfg x)) (snd (BDDvar_make cfg x)))
(bool_fun_var x).