+++ /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 *)
-(* *)
-(**************************************************************************)
-
-include "Ground_2/arith.ma".
-
-(* TRICOTOMY FUNCTION *******************************************************)
-
-let rec tri (A:Type[0]) m n a b c on m : A ≝
- match m with
- [ O ⇒ match n with [ O ⇒ b | S n ⇒ a ]
- | S m ⇒ match n with [ O ⇒ c | S n ⇒ tri A m n a b c ]
- ].
-
-(* Basic properties *********************************************************)
-
-lemma tri_lt: ∀A,a,b,c,n,m. m < n → tri A m n a b c = a.
-#A #a #b #c #n elim n -n
-[ #m #H elim (lt_zero_false … H)
-| #n #IH #m elim m -m // /3 width=1/
-]
-qed.
-
-lemma tri_eq: ∀A,a,b,c,m. tri A m m a b c = b.
-#A #a #b #c #m elim m -m normalize //
-qed.
-
-lemma tri_gt: ∀A,a,b,c,m,n. n < m → tri A m n a b c = c.
-#A #a #b #c #m elim m -m
-[ #n #H elim (lt_zero_false … H)
-| #m #IH #n elim n -n // /3 width=1/
-]
-qed.
-