simple induction 2; auto with pts; intros.
Inversion_typ H3.
apply typ_conv_wf with (Prod M U); auto with pts.
apply type_conv with (Prod M' U) s; auto with pts.
Inversion_typ H5.
apply type_abs with s3; auto with pts.
apply type_prod with s1 s2; auto with pts.
apply red_in_env with M s1; auto with pts.
apply red_in_env with M s1; auto with pts.
apply incl_R_le_type.
auto with pts.
apply type_correctness with (Abs M N); auto with pts.
Inversion_typ H3.
apply typ_conv_wf with (Prod N U); auto with pts.
apply type_abs with s; auto with pts.
apply type_correctness with (Abs N M); auto with pts.
Inversion_typ H3.
apply typ_conv_wf with (subst M2 Ur); auto with pts.
apply type_app with V; auto with pts.
apply type_correctness with (App M1 M2); auto with pts.
Inversion_typ H3.
apply typ_conv_wf with (subst M2 Ur); auto with pts.
cut (wf_type the_PTS e0 (Prod V Ur)); intros.
inversion_clear H7.
Inversion_typ H8.
apply type_conv with (subst N2 Ur) s2; auto with pts.
apply type_app with V; auto with pts.
apply red_incl_le_type.
unfold subst in |- *.
apply red_subst_l with e0; auto with pts.
replace (Srt s2) with (subst M2 (Srt s2)); auto with pts.
apply substitution with V; auto with pts.
apply type_correctness with M1; auto with pts.
apply type_correctness with (App M1 M2); auto with pts.
Inversion_typ H3.
apply typ_conv_wf with (Srt s3); auto with pts.
apply type_prod with s1 s2; auto with pts.
apply red_in_env with M1 s1; auto with pts.
apply type_correctness with (Prod M1 M2); auto with pts.
Inversion_typ H3.
apply typ_conv_wf with (Srt s3); auto with pts.
apply type_prod with s1 s2; auto with pts.
apply type_correctness with (Prod M1 M2); auto with pts.
Qed.
End Sound_context.

Theorem incl_sound :
forall P Q : red_rule,
(forall (e : env) (x y : term), P e x y -> Q e x y) ->
rule_sound Q -> rule_sound P.