--- /dev/null
+(**************************************************************************)
+(* ___ *)
+(* ||M|| *)
+(* ||A|| A project by Andrea Asperti *)
+(* ||T|| *)
+(* ||I|| Developers: *)
+(* ||T|| The HELM team. *)
+(* ||A|| http://helm.cs.unibo.it *)
+(* \ / *)
+(* \ / This file is distributed under the terms of the *)
+(* v GNU General Public License Version 2 *)
+(* *)
+(**************************************************************************)
+
+universe constraint Type[0] < Type[1].
+universe constraint Type[1] < Type[2].
+
+naxiom T : Type[0].
+naxiom P : T → T → CProp[0].
+naxiom Q : T → CProp[0].
+naxiom f : T → T → T.
+
+naxiom f_com : ∀x,y. P (f x y) (f y x).
+naxiom f_Q : ∀x,y. P x y → Q (f x y).
+
+nlemma foo : ∀x,y. Q x → Q (f (f x y) (f y x)).
+#x; #y; #H;
+ncut (Q x);
+##[##2: #_; nauto;
+##| nassumption;
+##]
+nqed.
+
+naxiom And : CProp[0] → CProp[0] → CProp[0].
+naxiom And_intro : ∀A,B.A → B → And A B.
+
+naxiom zero : T.
+naxiom succ : T → T.
+naxiom is_nat : T → CProp[0].
+naxiom is_nat_0 : is_nat zero.
+naxiom is_nat_S : ∀x.is_nat x → is_nat (succ x).
+
+nlemma bar : ∀P:T → CProp[0].P (succ zero) → (λx.And (is_nat x) (P x)) ?.
+##[ #P; #H; nwhd; napply And_intro; ##] nauto.
+nqed.
+
+naxiom A : CProp[0].
+naxiom pA : A.
+
+nlemma baz : ∀P,Q:CProp[0].(A → P) → (And A P → Q) → Q.
+nauto depth=3;
+nqed.
+
+nlemma traz:
+ ∀T:Type[0].
+ ∀And: CProp[0] → CProp[0] → CProp[0] → CProp[0].
+ ∀And_elim : ∀a,b,c.a → b → c → And a b c.
+ ∀C: T → T → T → CProp[0].
+ ∀B: T → T → CProp[0].
+ ∀A: T → CProp[0].
+ ∀a,b,c:T.
+ ∀p2:A b.
+ ∀p1:A a.
+ ∀p3:B a b.
+ ∀p3:B b b.
+ ∀p4:B b a.
+ ∀p3:B a a.
+ ∀p5:C a a a.
+ (λx,y,z:T.And (A x) (B x y) (C x y z)) ???.
+##[ #T; #And; #And_intro; #A; #B; #C; #a; #b; #p1; #p2; #p3; #p4; #p5;
+ #p6; #p7; nauto;
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