+interpretation "dependent pair" 'pair a b = (ex_introT _ _ a b).
+
+notation < "'fst' \nbsp x" non associative with precedence 90 for @{'pi1a $x}.
+notation < "'snd' \nbsp x" non associative with precedence 90 for @{'pi2a $x}.
+notation < "'fst' \nbsp x \nbsp y" non associative with precedence 90 for @{'pi1b $x $y}.
+notation < "'snd' \nbsp x \nbsp y" non associative with precedence 90 for @{'pi2b $x $y}.
+notation > "'fst'" non associative with precedence 90 for @{'pi1}.
+notation > "'snd'" non associative with precedence 90 for @{'pi2}.
+
+definition pi1exT ≝ λA,P.λx:exT A P.match x with [ex_introT x _ ⇒ x].
+definition pi2exT ≝
+ λA,P.λx:exT A P.match x return λx.P (pi1exT ?? x) with [ex_introT _ p ⇒ p].
+
+interpretation "exT fst" 'pi1 = (pi1exT _ _).
+interpretation "exT fst" 'pi1a x = (pi1exT _ _ x).
+interpretation "exT fst" 'pi1b x y = (pi1exT _ _ x y).
+interpretation "exT snd" 'pi2 = (pi2exT _ _).
+interpretation "exT snd" 'pi2a x = (pi2exT _ _ x).
+interpretation "exT snd" 'pi2b x y = (pi2exT _ _ x y).
+
+inductive exT23 (A:Type) (P:A→CProp) (Q:A→CProp) (R:A→A→CProp) : CProp ≝
+ ex_introT23: ∀w,p:A. P w → Q p → R w p → exT23 A P Q R.
+
+definition pi1exT23 ≝
+ λA,P,Q,R.λx:exT23 A P Q R.match x with [ex_introT23 x _ _ _ _ ⇒ x].
+definition pi2exT23 ≝
+ λA,P,Q,R.λx:exT23 A P Q R.match x with [ex_introT23 _ x _ _ _ ⇒ x].
+
+interpretation "exT2 fst" 'pi1 = (pi1exT23 _ _ _ _).
+interpretation "exT2 snd" 'pi2 = (pi2exT23 _ _ _ _).
+interpretation "exT2 fst" 'pi1a x = (pi1exT23 _ _ _ _ x).
+interpretation "exT2 snd" 'pi2a x = (pi2exT23 _ _ _ _ x).
+interpretation "exT2 fst" 'pi1b x y = (pi1exT23 _ _ _ _ x y).
+interpretation "exT2 snd" 'pi2b x y = (pi2exT23 _ _ _ _ x y).