interpretation "hide2" 'hide = (hide _ _ _).
definition inject ≝ λP.λa:nat.λp:P a. ex_introT ? P ? p.
-coercion cic:/matita/dama/russell_support/inject.con 0 1.
+coercion inject 0 1.
definition eject ≝ λP.λc: ∃n:nat.P n. match c with [ ex_introT w _ ⇒ w].
-coercion cic:/matita/dama/russell_support/eject.con.
+coercion eject.