helm/software/matita/library/dama/russell_support.ma

   1 (**************************************************************************)
   2 (*       ___                                                              *)
   3 (*      ||M||                                                             *)
   4 (*      ||A||       A project by Andrea Asperti                           *)
   5 (*      ||T||                                                             *)
   6 (*      ||I||       Developers:                                           *)
   7 (*      ||T||         The HELM team.                                      *)
   8 (*      ||A||         http://helm.cs.unibo.it                             *)
   9 (*      \   /                                                             *)
  10 (*       \ /        This file is distributed under the terms of the       *)
  11 (*        v         GNU General Public License Version 2                  *)
  12 (*                                                                        *)
  13 (**************************************************************************)
  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 inject 0 1.
  26 definition eject ≝ λP.λc: ∃n:nat.P n. match c with [ ex_introT w _ ⇒ w].
  27 coercion eject.