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4 (* ||A|| A project by Andrea Asperti *)
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7 (* ||T|| The HELM team. *)
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19 include "Init/Prelude.ma".
21 (*#***********************************************************************)
23 (* v * The Coq Proof Assistant / The Coq Development Team *)
25 (* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
27 (* \VV/ **************************************************************)
29 (* // * This file is distributed under the terms of the *)
31 (* * GNU Lesser General Public License Version 2.1 *)
33 (*#***********************************************************************)
35 (*i $Id: ChoiceFacts.v,v 1.7.2.2 2004/08/01 09:29:59 herbelin Exp $ i*)
37 (*#* We show that the functional formulation of the axiom of Choice
38 (usual formulation in type theory) is equivalent to its relational
39 formulation (only formulation of set theory) + the axiom of
40 (parametric) definite description (aka axiom of unique choice) *)
42 (*#* This shows that the axiom of choice can be assumed (under its
43 relational formulation) without known inconsistency with classical logic,
44 though definite description conflicts with classical logic *)
46 inline procedural "cic:/Coq/Logic/ChoiceFacts/RelationalChoice.con" as definition.
48 inline procedural "cic:/Coq/Logic/ChoiceFacts/FunctionalChoice.con" as definition.
50 inline procedural "cic:/Coq/Logic/ChoiceFacts/ParamDefiniteDescription.con" as definition.
52 inline procedural "cic:/Coq/Logic/ChoiceFacts/description_rel_choice_imp_funct_choice.con" as lemma.
54 inline procedural "cic:/Coq/Logic/ChoiceFacts/funct_choice_imp_rel_choice.con" as lemma.
56 inline procedural "cic:/Coq/Logic/ChoiceFacts/funct_choice_imp_description.con" as lemma.
58 inline procedural "cic:/Coq/Logic/ChoiceFacts/FunChoice_Equiv_RelChoice_and_ParamDefinDescr.con" as theorem.
60 (*#* We show that the guarded relational formulation of the axiom of Choice
61 comes from the non guarded formulation in presence either of the
62 independance of premises or proof-irrelevance *)
64 inline procedural "cic:/Coq/Logic/ChoiceFacts/GuardedRelationalChoice.con" as definition.
66 inline procedural "cic:/Coq/Logic/ChoiceFacts/ProofIrrelevance.con" as definition.
68 inline procedural "cic:/Coq/Logic/ChoiceFacts/rel_choice_and_proof_irrel_imp_guarded_rel_choice.con" as lemma.
70 inline procedural "cic:/Coq/Logic/ChoiceFacts/IndependenceOfPremises.con" as definition.
72 inline procedural "cic:/Coq/Logic/ChoiceFacts/rel_choice_indep_of_premises_imp_guarded_rel_choice.con" as lemma.