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use named types to force some constraints asap
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4 (*      ||A||       A project by Andrea Asperti                           *)
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11 (*        v         GNU General Public License Version 2                  *)
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14
15 include "nat/nat.ma".
16 include "logic/cprop_connectives.ma".
17
18 definition hide ≝ λT:Type.λx:T.x.
19
20 notation < "\blacksquare" non associative with precedence 50 for @{'hide}.
21 interpretation "hide" 'hide = (hide _ _).
22 interpretation "hide2" 'hide = (hide _ _ _).
23
24 definition inject ≝ λP.λa:nat.λp:P a. ex_introT ? P ? p.
25 coercion cic:/matita/dama/russell_support/inject.con 0 1.
26 definition eject ≝ λP.λc: ∃n:nat.P n. match c with [ ex_introT w _ ⇒ w].
27 coercion cic:/matita/dama/russell_support/eject.con.