diff options
Diffstat (limited to 'theories/Logic/Berardi.v')
| -rw-r--r-- | theories/Logic/Berardi.v | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/theories/Logic/Berardi.v b/theories/Logic/Berardi.v index d954f40c..38377573 100644 --- a/theories/Logic/Berardi.v +++ b/theories/Logic/Berardi.v @@ -1,13 +1,11 @@ (************************************************************************) (* v * The Coq Proof Assistant / The Coq Development Team *) -(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2011 *) +(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2012 *) (* \VV/ **************************************************************) (* // * This file is distributed under the terms of the *) (* * GNU Lesser General Public License Version 2.1 *) (************************************************************************) -(*i $Id: Berardi.v 14641 2011-11-06 11:59:10Z herbelin $ i*) - (** This file formalizes Berardi's paradox which says that in the calculus of constructions, excluded middle (EM) and axiom of choice (AC) imply proof irrelevance (PI). @@ -47,7 +45,7 @@ Lemma AC_IF : (B -> Q e1) -> (~ B -> Q e2) -> Q (IFProp B e1 e2). Proof. intros P B e1 e2 Q p1 p2. -unfold IFProp in |- *. +unfold IFProp. case (EM B); assumption. Qed. @@ -78,7 +76,7 @@ Record retract_cond : Prop := Lemma AC : forall r:retract_cond, retract -> forall a:A, j2 r (i2 r a) = a. Proof. intros r. -case r; simpl in |- *. +case r; simpl. trivial. Qed. @@ -115,7 +113,7 @@ Lemma retract_pow_U_U : retract (pow U) U. Proof. exists g f. intro a. -unfold f, g in |- *; simpl in |- *. +unfold f, g; simpl. apply AC. exists (fun x:pow U => x) (fun x:pow U => x). trivial. @@ -132,8 +130,8 @@ Definition R : U := g (fun u:U => Not_b (u U u)). Lemma not_has_fixpoint : R R = Not_b (R R). Proof. -unfold R at 1 in |- *. -unfold g in |- *. +unfold R at 1. +unfold g. rewrite AC with (r := L1 U U) (a := fun u:U => Not_b (u U u)). trivial. exists (fun x:pow U => x) (fun x:pow U => x); trivial. @@ -143,7 +141,7 @@ Qed. Theorem classical_proof_irrelevence : T = F. Proof. generalize not_has_fixpoint. -unfold Not_b in |- *. +unfold Not_b. apply AC_IF. intros is_true is_false. elim is_true; elim is_false; trivial. |