-interpretation "First projection" 'fst x =
- (cic:/matita/datatypes/constructors/fst.con _ _ x).
-
-notation "\fst x" with precedence 89
-for @{ 'fst $x}.
-
-interpretation "Second projection" 'snd x =
- (cic:/matita/datatypes/constructors/snd.con _ _ x).
-
-notation "\snd x" with precedence 89
-for @{ 'snd $x}.
+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).