fact: Fixpoint ext_exp (sigmaexp : fin -> exp ) (tauexp : fin -> exp ) (Eqexp : forall x, sigmaexp x = tauexp x) (s : exp ) : subst_exp sigmaexp s = subst_exp tauexp s := match s with | var_exp s => Eqexp s | const s0 => congr_const (eq_refl s0) | lam s0 => congr_lam (ext_exp (up_exp_exp sigmaexp) (up_exp_exp tauexp) (upExt_exp_exp (_) (_) Eqexp) s0) | app s0 s1 => congr_app (ext_exp sigmaexp tauexp Eqexp s0) (ext_exp sigmaexp tauexp Eqexp s1) end.
imports: Undecidability.HOU(std.std)