--- /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 "logic/pts.ma".
+
+nrecord pair (A,B: Type[0]) : Type[0] ≝
+ { fst: A;
+ snd: B
+ }.
+
+interpretation "Pair construction" 'pair x y = (mk_pair ? ? x y).
+
+interpretation "Product" 'product x y = (pair x y).
+
+interpretation "pair pi1" 'pi1 = (fst ? ?).
+interpretation "pair pi2" 'pi2 = (snd ? ?).
+interpretation "pair pi1" 'pi1a x = (fst ? ? x).
+interpretation "pair pi2" 'pi2a x = (snd ? ? x).
+interpretation "pair pi1" 'pi1b x y = (fst ? ? x y).
+interpretation "pair pi2" 'pi2b x y = (snd ? ? x y).