diff options
Diffstat (limited to 'theories/Logic/Diaconescu.v')
| -rw-r--r-- | theories/Logic/Diaconescu.v | 38 |
1 files changed, 19 insertions, 19 deletions
diff --git a/theories/Logic/Diaconescu.v b/theories/Logic/Diaconescu.v index b935a676..18f3181b 100644 --- a/theories/Logic/Diaconescu.v +++ b/theories/Logic/Diaconescu.v @@ -7,7 +7,7 @@ (* * GNU Lesser General Public License Version 2.1 *) (************************************************************************) -(*i $Id: Diaconescu.v 11481 2008-10-20 19:23:51Z herbelin $ i*) +(*i $Id$ i*) (** Diaconescu showed that the Axiom of Choice entails Excluded-Middle in topoi [Diaconescu75]. Lacas and Werner adapted the proof to show @@ -59,7 +59,7 @@ Definition PredicateExtensionality := Require Import ClassicalFacts. Variable pred_extensionality : PredicateExtensionality. - + Lemma prop_ext : forall A B:Prop, (A <-> B) -> A = B. Proof. intros A B H. @@ -99,11 +99,11 @@ Lemma AC_bool_subset_to_bool : (exists b : bool, P b) -> exists b : bool, P b /\ R P b /\ (forall b':bool, R P b' -> b = b')). Proof. - destruct (guarded_rel_choice _ _ + destruct (guarded_rel_choice _ _ (fun Q:bool -> Prop => exists y : _, Q y) (fun (Q:bool -> Prop) (y:bool) => Q y)) as (R,(HRsub,HR)). exact (fun _ H => H). - exists R; intros P HP. + exists R; intros P HP. destruct (HR P HP) as (y,(Hy,Huni)). exists y; firstorder. Qed. @@ -190,7 +190,7 @@ Lemma projT1_injective : a1=a2 -> a1'=a2'. Proof. intro Heq ; unfold a1', a2', A'. rewrite Heq. - replace (or_introl (a2=a2) (refl_equal a2)) + replace (or_introl (a2=a2) (refl_equal a2)) with (or_intror (a2=a2) (refl_equal a2)). reflexivity. apply proof_irrelevance. @@ -210,10 +210,10 @@ Qed. Theorem proof_irrel_rel_choice_imp_eq_dec : a1=a2 \/ ~a1=a2. Proof. - destruct - (rel_choice A' bool + destruct + (rel_choice A' bool (fun x y => projT1 x = a1 /\ y = true \/ projT1 x = a2 /\ y = false)) - as (R,(HRsub,HR)). + as (R,(HRsub,HR)). apply decide. destruct (HR a1') as (b1,(Ha1'b1,_Huni1)). destruct (HRsub a1' b1 Ha1'b1) as [(_, Hb1true)|(Ha1a2, _Hb1false)]. @@ -235,18 +235,18 @@ Declare Implicit Tactic auto. Lemma proof_irrel_rel_choice_imp_eq_dec' : a1=a2 \/ ~a1=a2. Proof. - assert (decide: forall x:A, x=a1 \/ x=a2 -> + assert (decide: forall x:A, x=a1 \/ x=a2 -> exists y:bool, x=a1 /\ y=true \/ x=a2 /\ y=false). intros a [Ha1|Ha2]; [exists true | exists false]; auto. - assert (guarded_rel_choice := - rel_choice_and_proof_irrel_imp_guarded_rel_choice - rel_choice + assert (guarded_rel_choice := + rel_choice_and_proof_irrel_imp_guarded_rel_choice + rel_choice proof_irrelevance). - destruct - (guarded_rel_choice A bool + destruct + (guarded_rel_choice A bool (fun x => x=a1 \/ x=a2) (fun x y => x=a1 /\ y=true \/ x=a2 /\ y=false)) - as (R,(HRsub,HR)). + as (R,(HRsub,HR)). apply decide. destruct (HR a1) as (b1,(Ha1b1,_Huni1)). left; reflexivity. destruct (HRsub a1 b1 Ha1b1) as [(_, Hb1true)|(Ha1a2, _Hb1false)]. @@ -273,8 +273,8 @@ Section ExtensionalEpsilon_imp_EM. Variable epsilon : forall A : Type, inhabited A -> (A -> Prop) -> A. -Hypothesis epsilon_spec : - forall (A:Type) (i:inhabited A) (P:A->Prop), +Hypothesis epsilon_spec : + forall (A:Type) (i:inhabited A) (P:A->Prop), (exists x, P x) -> P (epsilon A i P). Hypothesis epsilon_extensionality : @@ -288,9 +288,9 @@ Proof. intro P. pose (B := fun y => y=false \/ P). pose (C := fun y => y=true \/ P). - assert (B (eps B)) as [Hfalse|HP] + assert (B (eps B)) as [Hfalse|HP] by (apply epsilon_spec; exists false; left; reflexivity). - assert (C (eps C)) as [Htrue|HP] + assert (C (eps C)) as [Htrue|HP] by (apply epsilon_spec; exists true; left; reflexivity). right; intro HP. assert (forall y, B y <-> C y) by (intro y; split; intro; right; assumption). |