Mercurial > hg > Members > kono > Proof > ZF-in-agda
diff ODC.agda @ 279:197e0b3d39dc
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author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
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date | Sat, 09 May 2020 16:41:40 +0900 |
parents | d9d3654baee1 |
children | 5544f4921a44 |
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--- a/ODC.agda Sat May 09 09:40:18 2020 +0900 +++ b/ODC.agda Sat May 09 16:41:40 2020 +0900 @@ -94,47 +94,3 @@ choice : (X : OD ) → {A : OD } → ( X∋A : X ∋ A ) → (not : ¬ ( A == od∅ )) → A ∋ choice-func X not X∋A choice X {A} X∋A not = x∋minimal A not - --- With assuption of OD is ordered, p ∨ ( ¬ p ) <=> axiom of choice - --- - record choiced ( X : OD) : Set (suc n) where - field - a-choice : OD - is-in : X ∋ a-choice - - choice-func' : (X : OD ) → (p∨¬p : ( p : Set (suc n)) → p ∨ ( ¬ p )) → ¬ ( X == od∅ ) → choiced X - choice-func' X p∨¬p not = have_to_find where - ψ : ( ox : Ordinal ) → Set (suc n) - ψ ox = (( x : Ordinal ) → x o< ox → ( ¬ def X x )) ∨ choiced X - lemma-ord : ( ox : Ordinal ) → ψ ox - lemma-ord ox = TransFinite {ψ} induction ox where - ∋-p : (A x : OD ) → Dec ( A ∋ x ) - ∋-p A x with p∨¬p (Lift (suc n) ( A ∋ x )) -- LEM - ∋-p A x | case1 (lift t) = yes t - ∋-p A x | case2 t = no (λ x → t (lift x )) - ∀-imply-or : {A : Ordinal → Set n } {B : Set (suc n) } - → ((x : Ordinal ) → A x ∨ B) → ((x : Ordinal ) → A x) ∨ B - ∀-imply-or {A} {B} ∀AB with p∨¬p (Lift ( suc n ) ((x : Ordinal ) → A x)) -- LEM - ∀-imply-or {A} {B} ∀AB | case1 (lift t) = case1 t - ∀-imply-or {A} {B} ∀AB | case2 x = case2 (lemma (λ not → x (lift not ))) where - lemma : ¬ ((x : Ordinal ) → A x) → B - lemma not with p∨¬p B - lemma not | case1 b = b - lemma not | case2 ¬b = ⊥-elim (not (λ x → dont-orb (∀AB x) ¬b )) - induction : (x : Ordinal) → ((y : Ordinal) → y o< x → ψ y) → ψ x - induction x prev with ∋-p X ( ord→od x) - ... | yes p = case2 ( record { a-choice = ord→od x ; is-in = p } ) - ... | no ¬p = lemma where - lemma1 : (y : Ordinal) → (y o< x → def X y → ⊥) ∨ choiced X - lemma1 y with ∋-p X (ord→od y) - lemma1 y | yes y<X = case2 ( record { a-choice = ord→od y ; is-in = y<X } ) - lemma1 y | no ¬y<X = case1 ( λ lt y<X → ¬y<X (subst (λ k → def X k ) (sym diso) y<X ) ) - lemma : ((y : Ordinals.ord O) → (O Ordinals.o< y) x → def X y → ⊥) ∨ choiced X - lemma = ∀-imply-or lemma1 - have_to_find : choiced X - have_to_find = dont-or (lemma-ord (od→ord X )) ¬¬X∋x where - ¬¬X∋x : ¬ ((x : Ordinal) → x o< (od→ord X) → def X x → ⊥) - ¬¬X∋x nn = not record { - eq→ = λ {x} lt → ⊥-elim (nn x (def→o< lt) lt) - ; eq← = λ {x} lt → ⊥-elim ( ¬x<0 lt ) - } -