1) New file russell with the coercions to activate Russell-style proving.

[helm.git] / matita / matita / lib / basics / russell.ma

diff --git a/matita/matita/lib/basics/russell.ma b/matita/matita/lib/basics/russell.ma
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+(*
+    ||M||  This file is part of HELM, an Hypertextual, Electronic        
+    ||A||  Library of Mathematics, developed at the Computer Science     
+    ||T||  Department of the University of Bologna, Italy.                     
+    ||I||                                                                 
+    ||T||  
+    ||A||  
+    \   /  This file is distributed under the terms of the       
+     \ /   GNU General Public License Version 2   
+      V_______________________________________________________________ *)
+
+include "basics/jmeq.ma".
+include "basics/types.ma".
+
+definition inject : ∀A.∀P:A → Prop.∀a.∀p:P a.Σx:A.P x ≝ λA,P,a,p. mk_Sig … a p.
+definition eject : ∀A.∀P: A → Prop.(Σx:A.P x) → A ≝ λA,P,c.pi1 … c.
+
+coercion inject nocomposites: ∀A.∀P:A → Prop.∀a.∀p:P a.Σx:A.P x ≝ inject on a:? to Σx:?.?.
+coercion eject nocomposites: ∀A.∀P:A → Prop.∀c:Σx:A.P x.A ≝ eject on _c:Σx:?.? to ?.