fact: Definition formula_val_aux X x f (t:= P x) := Yo (P x = val_in) (Val_of_inc X (P (Q x)) (Q (Q x))) (Yo (P x = val_eq) (Val_of_eq X (P (Q x)) (Q (Q x))) (Yo (P x = val_not) (Val_of_not X (free_vars x) (Vg f (Q x))) (Yo (P x = val_or) (Val_of_or X (free_vars (P (Q x))) (free_vars (Q (Q x))) (Vg f (P (Q x))) (Vg f (Q (Q x)))) (Val_of_ex X (free_vars x) (Vg f (Q (Q x))))))).
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)