Mercurial > hg > Members > kono > Proof > ZF-in-agda
view src/ZProduct.agda @ 1324:1eefc6600354
...
| author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Sun, 11 Jun 2023 18:49:13 +0900 |
| parents | 66a6804d867b |
| children | a7d46b1c2a70 |
line wrap: on
line source
{-# OPTIONS --allow-unsolved-metas #-} open import Level open import Ordinals module ZProduct {n : Level } (O : Ordinals {n}) where open import logic import OD import ODUtil import OrdUtil open import Relation.Nullary open import Relation.Binary open import Data.Empty open import Relation.Binary open import Relation.Binary.Core open import Relation.Binary.PropositionalEquality open import Data.Nat renaming ( zero to Zero ; suc to Suc ; ℕ to Nat ; _⊔_ to _n⊔_ ) open OD O open OD.OD open OD.HOD open ODAxiom odAxiom open Ordinals.Ordinals O open Ordinals.IsOrdinals isOrdinal -- open Ordinals.IsNext isNext open OrdUtil O open ODUtil O open _∧_ open _∨_ open Bool open _==_ <_,_> : (x y : HOD) → HOD < x , y > = (x , x ) , (x , y ) ZFP<AB : {X Y x y : HOD} → X ∋ x → Y ∋ y → < x , y > ⊆ Power ( Union (X , Y )) ZFP<AB {X} {Y} {x} {y} xx yy (case1 refl ) z lt with subst (λ k → odef k z) *iso lt ... | case1 refl = record { owner = _ ; ao = case1 refl ; ox = subst₂ (λ j k → odef j k) (sym *iso) refl xx } ... | case2 refl = record { owner = _ ; ao = case1 refl ; ox = subst₂ (λ j k → odef j k) (sym *iso) refl xx } ZFP<AB {X} {Y} {x} {y} xx yy (case2 refl ) z lt with subst (λ k → odef k z) *iso lt ... | case1 refl = record { owner = _ ; ao = case1 refl ; ox = subst₂ (λ j k → odef j k) (sym *iso) refl xx } ... | case2 refl = record { owner = _ ; ao = case2 refl ; ox = subst₂ (λ j k → odef j k) (sym *iso) refl yy } exg-pair : { x y : HOD } → (x , y ) =h= ( y , x ) exg-pair {x} {y} = record { eq→ = left ; eq← = right } where left : {z : Ordinal} → odef (x , y) z → odef (y , x) z left (case1 t) = case2 t left (case2 t) = case1 t right : {z : Ordinal} → odef (y , x) z → odef (x , y) z right (case1 t) = case2 t right (case2 t) = case1 t ord≡→≡ : { x y : HOD } → & x ≡ & y → x ≡ y ord≡→≡ eq = subst₂ (λ j k → j ≡ k ) *iso *iso ( cong ( λ k → * k ) eq ) od≡→≡ : { x y : Ordinal } → * x ≡ * y → x ≡ y od≡→≡ eq = subst₂ (λ j k → j ≡ k ) &iso &iso ( cong ( λ k → & k ) eq ) eq-prod : { x x' y y' : HOD } → x ≡ x' → y ≡ y' → < x , y > ≡ < x' , y' > eq-prod refl refl = refl xx=zy→x=y : {x y z : HOD } → ( x , x ) =h= ( z , y ) → x ≡ y xx=zy→x=y {x} {y} eq with trio< (& x) (& y) xx=zy→x=y {x} {y} eq | tri< a ¬b ¬c with eq← eq {& y} (case2 refl) xx=zy→x=y {x} {y} eq | tri< a ¬b ¬c | case1 s = ⊥-elim ( o<¬≡ (sym s) a ) xx=zy→x=y {x} {y} eq | tri< a ¬b ¬c | case2 s = ⊥-elim ( o<¬≡ (sym s) a ) xx=zy→x=y {x} {y} eq | tri≈ ¬a b ¬c = ord≡→≡ b xx=zy→x=y {x} {y} eq | tri> ¬a ¬b c with eq← eq {& y} (case2 refl) xx=zy→x=y {x} {y} eq | tri> ¬a ¬b c | case1 s = ⊥-elim ( o<¬≡ s c ) xx=zy→x=y {x} {y} eq | tri> ¬a ¬b c | case2 s = ⊥-elim ( o<¬≡ s c ) prod-eq : { x x' y y' : HOD } → < x , y > =h= < x' , y' > → (x ≡ x' ) ∧ ( y ≡ y' ) prod-eq {x} {x'} {y} {y'} eq = ⟪ lemmax , lemmay ⟫ where lemma2 : {x y z : HOD } → ( x , x ) =h= ( z , y ) → z ≡ y lemma2 {x} {y} {z} eq = trans (sym (xx=zy→x=y lemma3 )) ( xx=zy→x=y eq ) where lemma3 : ( x , x ) =h= ( y , z ) lemma3 = ==-trans eq exg-pair lemma1 : {x y : HOD } → ( x , x ) =h= ( y , y ) → x ≡ y lemma1 {x} {y} eq with eq← eq {& y} (case2 refl) lemma1 {x} {y} eq | case1 s = ord≡→≡ (sym s) lemma1 {x} {y} eq | case2 s = ord≡→≡ (sym s) lemma4 : {x y z : HOD } → ( x , y ) =h= ( x , z ) → y ≡ z lemma4 {x} {y} {z} eq with eq← eq {& z} (case2 refl) lemma4 {x} {y} {z} eq | case1 s with ord≡→≡ s -- x ≡ z ... | refl with lemma2 (==-sym eq ) ... | refl = refl lemma4 {x} {y} {z} eq | case2 s = ord≡→≡ (sym s) -- y ≡ z lemmax : x ≡ x' lemmax with eq→ eq {& (x , x)} (case1 refl) lemmax | case1 s = lemma1 (ord→== s ) -- (x,x)≡(x',x') lemmax | case2 s with lemma2 (ord→== s ) -- (x,x)≡(x',y') with x'≡y' ... | refl = lemma1 (ord→== s ) lemmay : y ≡ y' lemmay with lemmax ... | refl with lemma4 eq -- with (x,y)≡(x,y') ... | eq1 = lemma4 (ord→== (cong (λ k → & k ) eq1 )) prod-≡ : { x x' y y' : HOD } → < x , y > ≡ < x' , y' > → (x ≡ x' ) ∧ ( y ≡ y' ) prod-≡ eq = prod-eq (ord→== (cong (&) eq )) -- -- unlike ordered pair, ZFPair is not a HOD data ord-pair : (p : Ordinal) → Set n where pair : (x y : Ordinal ) → ord-pair ( & ( < * x , * y > ) ) ZFPair : OD ZFPair = record { def = λ x → ord-pair x } -- _⊗_ : (A B : HOD) → HOD -- A ⊗ B = Union ( Replace' B (λ b lb → Replace' A (λ a la → < a , b > ) record { ≤COD = ? } ) ? ) -- product→ : {A B a b : HOD} → A ∋ a → B ∋ b → ( A ⊗ B ) ∋ < a , b > -- product→ {A} {B} {a} {b} A∋a B∋b = record { owner = _ ; ao = lemma1 ; ox = subst (λ k → odef k _) (sym *iso) lemma2 } where -- lemma1 : odef (Replace' B (λ b₁ lb → Replace' A (λ a₁ la → < a₁ , b₁ >) ? ) ? ) (& (Replace' A (λ a₁ la → < a₁ , b >) ? )) -- lemma1 = ? -- replacement← B b B∋b ? -- lemma2 : odef (Replace' A (λ a₁ la → < a₁ , b >) ? ) (& < a , b >) -- lemma2 = ? -- replacement← A a A∋a ? data ZFProduct (A B : HOD) : (p : Ordinal) → Set n where ab-pair : {a b : Ordinal } → odef A a → odef B b → ZFProduct A B ( & ( < * a , * b > ) ) ZFP : (A B : HOD) → HOD ZFP A B = record { od = record { def = λ x → ZFProduct A B x } ; odmax = osuc (& ( Power ( Union (A , B )))) ; <odmax = λ {y} px → lemma0 px } where lemma0 : {x : Ordinal } → ZFProduct A B x → x o< osuc (& ( Power ( Union (A , B )) )) lemma0 ( ab-pair {a} {b} ax by ) = lemma1 where lemma1 : & < * a , * b > o< osuc (& (Power (Union (A , B)))) lemma1 = ⊆→o≤ (ZFP<AB (subst (λ k → odef A k) (sym &iso) ax) (subst (λ k → odef B k) (sym &iso) by) ) ZFP→ : {A B a b : HOD} → A ∋ a → B ∋ b → ZFP A B ∋ < a , b > ZFP→ {A} {B} {a} {b} aa bb = subst (λ k → ZFProduct A B k ) (cong₂ (λ j k → & < j , k >) *iso *iso ) ( ab-pair aa bb ) zπ1 : {A B : HOD} → {x : Ordinal } → odef (ZFP A B) x → Ordinal zπ1 {A} {B} {.(& < * _ , * _ >)} (ab-pair {a} {b} aa bb) = a zp1 : {A B : HOD} → {x : Ordinal } → (zx : odef (ZFP A B) x) → odef A (zπ1 zx) zp1 {A} {B} {.(& < * _ , * _ >)} (ab-pair {a} {b} aa bb ) = aa zπ2 : {A B : HOD} → {x : Ordinal } → odef (ZFP A B) x → Ordinal zπ2 (ab-pair {a} {b} aa bb) = b zp2 : {A B : HOD} → {x : Ordinal } → (zx : odef (ZFP A B) x) → odef B (zπ2 zx) zp2 {A} {B} {.(& < * _ , * _ >)} (ab-pair {a} {b} aa bb ) = bb zp-iso : { A B : HOD } → {x : Ordinal } → (p : odef (ZFP A B) x ) → & < * (zπ1 p) , * (zπ2 p) > ≡ x zp-iso {A} {B} {_} (ab-pair {a} {b} aa bb) = refl zp-iso1 : { A B : HOD } → {a b : Ordinal } → (p : odef (ZFP A B) (& < * a , * b > )) → (* (zπ1 p) ≡ (* a)) ∧ (* (zπ2 p) ≡ (* b)) zp-iso1 {A} {B} {a} {b} pab = prod-≡ (subst₂ (λ j k → j ≡ k ) *iso *iso (cong (*) zz11) ) where zz11 : & < * (zπ1 pab) , * (zπ2 pab) > ≡ & < * a , * b > zz11 = zp-iso pab zp-iso0 : { A B : HOD } → {a b : Ordinal } → (p : odef (ZFP A B) (& < * a , * b > )) → (zπ1 p ≡ a) ∧ (zπ2 p ≡ b) zp-iso0 {A} {B} {a} {b} pab = ⟪ subst₂ (λ j k → j ≡ k ) &iso &iso (cong (&) (proj1 (zp-iso1 pab) )) , subst₂ (λ j k → j ≡ k ) &iso &iso (cong (&) (proj2 (zp-iso1 pab) ) ) ⟫ -- ZFP⊆⊗ : {A B : HOD} {x : Ordinal} → odef (ZFP A B) x → odef (A ⊗ B) x -- ZFP⊆⊗ {A} {B} {px} ( ab-pair {a} {b} ax by ) = product→ (d→∋ A ax) (d→∋ B by) -- ⊗⊆ZFP : {A B x : HOD} → ( A ⊗ B ) ∋ x → odef (ZFP A B) (& x) -- ⊗⊆ZFP {A} {B} {x} record { owner = owner ; ao = record { z = a ; az = ba ; x=ψz = x=ψa } ; ox = ox } = zfp01 where -- zfp02 : Replace' A (λ z lz → < z , * a >) record { ≤COD = ? } ≡ * owner -- zfp02 = subst₂ ( λ j k → j ≡ k ) *iso refl (sym (cong (*) x=ψa )) -- zfp01 : odef (ZFP A B) (& x) -- zfp01 with subst (λ k → odef k (& x) ) (sym zfp02) ox -- ... | t = ? -- -- ... | record { z = b ; az = ab ; x=ψz = x=ψb } = subst (λ k → ZFProduct A B k ) (sym x=ψb) (ab-pair ab ba) ZPI1 : (A B : HOD) → HOD ZPI1 A B = Replace' (ZFP A B) ( λ x px → * (zπ1 px )) {Union A} record { ≤COD = lemma1 } where lemma1 : {x : Ordinal } (lt : odef (ZFP A B) x) → * (zπ1 lt) ⊆ Union A lemma1 (ab-pair {a} {b} aa bb) {x} ax = record { owner = _ ; ao = aa ; ox = ax } ZPI2 : (A B : HOD) → HOD ZPI2 A B = Replace' (ZFP A B) ( λ x px → * (zπ2 px )) {Union B} record { ≤COD = lemma1 } where lemma1 : {x : Ordinal } (lt : odef (ZFP A B) x) → * (zπ2 lt) ⊆ Union B lemma1 (ab-pair {a} {b} aa bb) {x} bx = record { owner = _ ; ao = bb ; ox = bx } ZFProj1-iso : {P Q : HOD} {a b x : Ordinal } ( p : ZFProduct P Q x ) → x ≡ & < * a , * b > → zπ1 p ≡ a ZFProj1-iso {P} {Q} {a} {b} (ab-pair {c} {d} zp zq) eq with prod-≡ (subst₂ (λ j k → j ≡ k) *iso *iso (cong (*) eq)) ... | ⟪ a=c , b=d ⟫ = subst₂ (λ j k → j ≡ k) &iso &iso (cong (&) a=c) ZFProj2-iso : {P Q : HOD} {a b x : Ordinal } ( p : ZFProduct P Q x ) → x ≡ & < * a , * b > → zπ2 p ≡ b ZFProj2-iso {P} {Q} {a} {b} (ab-pair {c} {d} zp zq) eq with prod-≡ (subst₂ (λ j k → j ≡ k) *iso *iso (cong (*) eq)) ... | ⟪ a=c , b=d ⟫ = subst₂ (λ j k → j ≡ k) &iso &iso (cong (&) b=d) ZPI1-iso : (A B : HOD) → {b : Ordinal } → odef B b → ZPI1 A B ≡ A ZPI1-iso P Q {q} qq = ==→o≡ record { eq→ = ty20 ; eq← = ty22 } where ty21 : {a b : Ordinal } → (pz : odef P a) → (qz : odef Q b) → ZFProduct P Q (& (* (& < * a , * b >))) ty21 pz qz = subst (odef (ZFP P Q)) (sym &iso) (ab-pair pz qz ) ty32 : {a b : Ordinal } → (pz : odef P a) → (qz : odef Q b) → zπ1 (ty21 pz qz) ≡ a ty32 {a} {b} pz qz = ty33 (ty21 pz qz) (cong (&) *iso) where ty33 : {a b x : Ordinal } ( p : ZFProduct P Q x ) → x ≡ & < * a , * b > → zπ1 p ≡ a ty33 {a} {b} (ab-pair {c} {d} zp zq) eq with prod-≡ (subst₂ (λ j k → j ≡ k) *iso *iso (cong (*) eq)) ... | ⟪ a=c , b=d ⟫ = subst₂ (λ j k → j ≡ k) &iso &iso (cong (&) a=c) ty20 : {x : Ordinal} → odef (ZPI1 P Q) x → odef P x ty20 {x} record { z = _ ; az = ab-pair {a} {b} pz qz ; x=ψz = x=ψz } = subst (λ k → odef P k) a=x pz where ty24 : * x ≡ * a ty24 = begin * x ≡⟨ cong (*) x=ψz ⟩ _ ≡⟨ *iso ⟩ * (zπ1 (subst (odef (ZFP P Q)) (sym &iso) (ab-pair pz qz))) ≡⟨ cong (*) (ty32 pz qz) ⟩ * a ∎ where open ≡-Reasoning a=x : a ≡ x a=x = subst₂ (λ j k → j ≡ k ) &iso &iso (cong (&) (sym ty24)) ty22 : {x : Ordinal} → odef P x → odef (ZPI1 P Q) x ty22 {x} px = record { z = _ ; az = ab-pair px qq ; x=ψz = subst₂ (λ j k → j ≡ k) &iso refl (cong (&) ty12 ) } where ty12 : * x ≡ * (zπ1 (subst (odef (ZFP P Q)) (sym &iso) (ab-pair px qq ))) ty12 = begin * x ≡⟨ sym (cong (*) (ty32 px qq )) ⟩ * (zπ1 (subst (odef (ZFP P Q)) (sym &iso) (ab-pair px qq ))) ∎ where open ≡-Reasoning ZPI2-iso : (A B : HOD) → {b : Ordinal } → odef A b → ZPI2 A B ≡ B ZPI2-iso P Q {p} pp = ==→o≡ record { eq→ = ty20 ; eq← = ty22 } where ty21 : {a b : Ordinal } → (pz : odef P a) → (qz : odef Q b) → ZFProduct P Q (& (* (& < * a , * b >))) ty21 pz qz = subst (odef (ZFP P Q)) (sym &iso) (ab-pair pz qz ) ty32 : {a b : Ordinal } → (pz : odef P a) → (qz : odef Q b) → zπ2 (ty21 pz qz) ≡ b ty32 {a} {b} pz qz = ty33 (ty21 pz qz) (cong (&) *iso) where ty33 : {a b x : Ordinal } ( p : ZFProduct P Q x ) → x ≡ & < * a , * b > → zπ2 p ≡ b ty33 {a} {b} (ab-pair {c} {d} zp zq) eq with prod-≡ (subst₂ (λ j k → j ≡ k) *iso *iso (cong (*) eq)) ... | ⟪ a=c , b=d ⟫ = subst₂ (λ j k → j ≡ k) &iso &iso (cong (&) b=d) ty20 : {x : Ordinal} → odef (ZPI2 P Q) x → odef Q x ty20 {x} record { z = _ ; az = ab-pair {a} {b} pz qz ; x=ψz = x=ψz } = subst (λ k → odef Q k) a=x qz where ty24 : * x ≡ * b ty24 = begin * x ≡⟨ cong (*) x=ψz ⟩ _ ≡⟨ *iso ⟩ * (zπ2 (subst (odef (ZFP P Q)) (sym &iso) (ab-pair pz qz))) ≡⟨ cong (*) (ty32 pz qz) ⟩ * b ∎ where open ≡-Reasoning a=x : b ≡ x a=x = subst₂ (λ j k → j ≡ k ) &iso &iso (cong (&) (sym ty24)) ty22 : {x : Ordinal} → odef Q x → odef (ZPI2 P Q) x ty22 {x} qx = record { z = _ ; az = ab-pair pp qx ; x=ψz = subst₂ (λ j k → j ≡ k) &iso refl (cong (&) ty12 ) } where ty12 : * x ≡ * (zπ2 (subst (odef (ZFP P Q)) (sym &iso) (ab-pair pp qx))) ty12 = begin * x ≡⟨ sym (cong (*) (ty32 pp qx )) ⟩ * (zπ2 (subst (odef (ZFP P Q)) (sym &iso) (ab-pair pp qx ))) ∎ where open ≡-Reasoning record ZP1 (A B C : HOD) ( cab : C ⊆ ZFP A B ) (a : Ordinal) : Set n where field b : Ordinal aa : odef A a bb : odef B b c∋ab : odef C (& < * a , * b > ) ZP-proj1 : (A B C : HOD) → C ⊆ ZFP A B → HOD ZP-proj1 A B C cab = record { od = record { def = λ x → ZP1 A B C cab x } ; odmax = & A ; <odmax = λ lt → odef< (ZP1.aa lt) } ZP-proj1⊆ZFP : {A B C : HOD} → {cab : C ⊆ ZFP A B} → C ⊆ ZFP (ZP-proj1 A B C cab) B ZP-proj1⊆ZFP {A} {B} {C} {cab} {c} cc with cab cc ... | ab-pair {a} {b} aa bb = ab-pair record { b = _ ; aa = aa ; bb = bb ; c∋ab = cc } bb ZP-proj1=rev : {A B a m : HOD} {b : Ordinal } → {cab : m ⊆ ZFP A B} → odef B b → a ⊆ A → m ≡ ZFP a B → a ≡ ZP-proj1 A B m cab ZP-proj1=rev {A} {B} {a} {m} {b} {cab} bb a⊆A refl = ==→o≡ record { eq→ = zp00 ; eq← = zp01 } where zp00 : {x : Ordinal } → odef a x → ZP1 A B (ZFP a B) cab x zp00 {x} ax = record { b = _ ; aa = a⊆A ax ; bb = bb ; c∋ab = ab-pair ax bb } zp01 : {x : Ordinal } → ZP1 A B (ZFP a B) cab x → odef a x zp01 {x} record { b = b ; aa = aa ; bb = bb ; c∋ab = c∋ab } = zp02 c∋ab refl where zp02 : {z : Ordinal } → odef (ZFP a B) z → z ≡ & < * x , * b > → odef a x zp02 {.(& < * _ , * _ >)} (ab-pair {a1} {b1} aa1 bb1) eq = subst (λ k → odef a k) (*≡*→≡ zp03) aa1 where zp03 : * a1 ≡ * x zp03 = proj1 (prod-≡ (&≡&→≡ eq)) ZP-proj1-0 : {A B : HOD} {z : Ordinal } → {zab : * z ⊆ ZFP A B} → ZP-proj1 A B (* z) zab ≡ od∅ → z ≡ & od∅ ZP-proj1-0 {A} {B} {z} {zab} eq = uf10 where uf10 : z ≡ & od∅ uf10 = trans (sym &iso) ( cong (&) (¬x∋y→x≡od∅ (λ {y} zy → uf11 zy ) )) where uf11 : {y : Ordinal } → odef (* z) y → ⊥ uf11 {y} zy = ⊥-elim ( ¬x<0 (subst (λ k → odef k (zπ1 pqy)) eq uf12 ) ) where pqy : odef (ZFP A B) y pqy = zab zy uf14 : odef (* z) (& < * (zπ1 pqy) , * (zπ2 pqy) >) uf14 = subst (λ k → odef (* z) k ) (sym ( zp-iso pqy)) zy uf12 : odef (ZP-proj1 A B (* z) zab) (zπ1 pqy) uf12 = record { b = _ ; aa = zp1 pqy ; bb = zp2 pqy ; c∋ab = uf14 } record ZP2 (A B C : HOD) ( cab : C ⊆ ZFP A B ) (b : Ordinal) : Set n where field a : Ordinal aa : odef A a bb : odef B b c∋ab : odef C (& < * a , * b > ) ZP-proj2 : (A B C : HOD) → C ⊆ ZFP A B → HOD ZP-proj2 A B C cab = record { od = record { def = λ x → ZP2 A B C cab x } ; odmax = & B ; <odmax = λ lt → odef< (ZP2.bb lt) } ZP-proj2⊆ZFP : {A B C : HOD} → {cab : C ⊆ ZFP A B} → C ⊆ ZFP A (ZP-proj2 A B C cab) ZP-proj2⊆ZFP {A} {B} {C} {cab} {c} cc with cab cc ... | ab-pair {a} {b} aa bb = ab-pair aa record { a = _ ; aa = aa ; bb = bb ; c∋ab = cc } ZP-proj2=rev : {A B a m : HOD} {b : Ordinal } → {cab : m ⊆ ZFP A B} → odef A b → a ⊆ B → m ≡ ZFP A a → a ≡ ZP-proj2 A B m cab ZP-proj2=rev {A} {B} {a} {m} {b} {cab} bb a⊆A refl = ==→o≡ record { eq→ = zp00 ; eq← = zp01 } where zp00 : {x : Ordinal } → odef a x → ZP2 A B (ZFP A a ) cab x zp00 {x} ax = record { a = _ ; aa = bb ; bb = a⊆A ax ; c∋ab = ab-pair bb ax } zp01 : {x : Ordinal } → ZP2 A B (ZFP A a ) cab x → odef a x zp01 {x} record { a = b ; aa = aa ; bb = bb ; c∋ab = c∋ab } = zp02 c∋ab refl where zp02 : {z : Ordinal } → odef (ZFP A a ) z → z ≡ & < * b , * x > → odef a x zp02 {.(& < * _ , * _ >)} (ab-pair {a1} {b1} aa1 bb1) eq = subst (λ k → odef a k) (*≡*→≡ zp03) bb1 where zp03 : * b1 ≡ * x zp03 = proj2 (prod-≡ (&≡&→≡ eq)) ZP-proj2-0 : {A B : HOD} {z : Ordinal } → {zab : * z ⊆ ZFP A B} → ZP-proj2 A B (* z) zab ≡ od∅ → z ≡ & od∅ ZP-proj2-0 {A} {B} {z} {zab} eq = uf10 where uf10 : z ≡ & od∅ uf10 = trans (sym &iso) ( cong (&) (¬x∋y→x≡od∅ (λ {y} zy → uf11 zy ) )) where uf11 : {y : Ordinal } → odef (* z) y → ⊥ uf11 {y} zy = ⊥-elim ( ¬x<0 (subst (λ k → odef k (zπ2 pqy)) eq uf12 ) ) where pqy : odef (ZFP A B) y pqy = zab zy uf14 : odef (* z) (& < * (zπ1 pqy) , * (zπ2 pqy) >) uf14 = subst (λ k → odef (* z) k ) (sym ( zp-iso pqy)) zy uf12 : odef (ZP-proj2 A B (* z) zab) (zπ2 pqy) uf12 = record { a = _ ; aa = zp1 pqy ; bb = zp2 pqy ; c∋ab = uf14 } record Func (A B : HOD) : Set n where field func : {x : Ordinal } → odef A x → Ordinal is-func : {x : Ordinal } → (ax : odef A x) → odef B (func ax ) fodmax : RXCod A (Power (Union (A , B))) (λ x ax → < x , * (func ax) >) fodmax = record { ≤COD = λ {x} ax → lemma1 ax } where lemma1 : {x : HOD} → (ax : odef A (& x)) → < x , * (func ax) > ⊆ Power (Union (A , B)) lemma1 {x} ax = ZFP<AB ax (subst (λ k → odef B k) (sym &iso) ( is-func ax ) ) data FuncHOD (A B : HOD) : (x : Ordinal) → Set n where felm : (F : Func A B) → FuncHOD A B (& ( Replace' A ( λ x ax → < x , (* (Func.func F {& x} ax )) > ) (Func.fodmax F) )) FuncHOD→F : {A B : HOD} {x : Ordinal} → FuncHOD A B x → Func A B FuncHOD→F {A} {B} (felm F) = F FuncHOD=R : {A B : HOD} {x : Ordinal} → (fc : FuncHOD A B x) → (* x) ≡ Replace' A ( λ x ax → < x , (* (Func.func (FuncHOD→F fc) ax)) > ) (Func.fodmax (FuncHOD→F fc) ) FuncHOD=R {A} {B} (felm F) = *iso -- -- Set of All function from A to B -- open import Relation.Binary.HeterogeneousEquality as HE using (_≅_ ) Funcs : (A B : HOD) → HOD Funcs A B = record { od = record { def = λ x → FuncHOD A B x } ; odmax = osuc (& (ZFP A B)) ; <odmax = λ {y} px → subst ( λ k → k o≤ (& (ZFP A B)) ) &iso (⊆→o≤ (lemma1 px)) } where lemma1 : {y : Ordinal } → FuncHOD A B y → {x : Ordinal} → odef (* y) x → odef (ZFP A B) x lemma1 {y} (felm F) {x} yx with subst (λ k → odef k x) *iso yx ... | record { z = z ; az = az ; x=ψz = x=ψz } = subst (λ k → ZFProduct A B k) (sym x=ψz) lemma4 where lemma4 : ZFProduct A B (& < * z , * (Func.func F (subst (λ k → odef A k) (sym &iso) az)) > ) lemma4 = ab-pair az (Func.is-func F (subst (λ k → odef A k) (sym &iso) az)) TwoHOD : HOD TwoHOD = ( od∅ , ( od∅ , od∅ )) Aleph1 : HOD Aleph1 = Funcs Omega TwoHOD record Injection (A B : Ordinal ) : Set n where field i→ : (x : Ordinal ) → odef (* A) x → Ordinal iB : (x : Ordinal ) → ( lt : odef (* A) x ) → odef (* B) ( i→ x lt ) inject : (x y : Ordinal ) → ( ltx : odef (* A) x ) ( lty : odef (* A) y ) → i→ x ltx ≡ i→ y lty → x ≡ y record HODBijection (A B : HOD ) : Set n where field fun← : (x : Ordinal ) → odef A x → Ordinal fun→ : (x : Ordinal ) → odef B x → Ordinal funB : (x : Ordinal ) → ( lt : odef A x ) → odef B ( fun← x lt ) funA : (x : Ordinal ) → ( lt : odef B x ) → odef A ( fun→ x lt ) fiso← : (x : Ordinal ) → ( lt : odef B x ) → fun← ( fun→ x lt ) ( funA x lt ) ≡ x fiso→ : (x : Ordinal ) → ( lt : odef A x ) → fun→ ( fun← x lt ) ( funB x lt ) ≡ x hodbij-refl : { a b : HOD } → a ≡ b → HODBijection a b hodbij-refl {a} refl = record { fun← = λ x _ → x ; fun→ = λ x _ → x ; funB = λ x lt → lt ; funA = λ x lt → lt ; fiso← = λ x lt → refl ; fiso→ = λ x lt → refl } pj12 : (A B : HOD) {x : Ordinal} → (ab : odef (ZFP A B) x ) → (zπ1 (subst (odef (ZFP A B)) (sym &iso) ab) ≡ & (* (zπ1 ab ))) ∧ (zπ2 (subst (odef (ZFP A B)) (sym &iso) ab) ≡ & (* (zπ2 ab ))) pj12 A B (ab-pair {x} {y} ax by) = ⟪ subst₂ (λ j k → j ≡ k ) &iso &iso (cong (&) (proj1 (prod-≡ pj24 ))) , subst₂ (λ j k → j ≡ k ) &iso &iso (cong (&) (proj2 (prod-≡ pj24))) ⟫ where pj22 : odef (ZFP A B) (& (* (& < * x , * y >))) pj22 = subst (odef (ZFP A B)) (sym &iso) (ab-pair ax by) pj23 : & < * (zπ1 pj22 ) , * (zπ2 pj22) > ≡ & (* (& < * x , * y >) ) pj23 = zp-iso pj22 pj24 : < * (zπ1 (subst (odef (ZFP A B)) (sym &iso) (ab-pair ax by))) , * (zπ2 (subst (odef (ZFP A B)) (sym &iso) (ab-pair ax by))) > ≡ < * (& (* x)) , * (& (* y)) > pj24 = subst₂ (λ j k → j ≡ k ) *iso *iso (cong (*) ( trans pj23 (trans &iso (sym (cong (&) (cong₂ (λ j k → < j , k >) *iso *iso)) )))) pj02 : (A B : HOD) (x : Ordinal) → (ab : odef (ZFP A B) x ) → odef (ZPI2 A B) (zπ2 ab) pj02 A B x ab = record { z = _ ; az = ab ; x=ψz = trans (sym &iso) (trans ( sym (proj2 (pj12 A B ab))) (sym &iso)) } pj01 : (A B : HOD) (x : Ordinal) → (ab : odef (ZFP A B) x ) → odef (ZPI1 A B) (zπ1 ab) pj01 A B x ab = record { z = _ ; az = ab ; x=ψz = trans (sym &iso) (trans ( sym (proj1 (pj12 A B ab))) (sym &iso)) } pj2 : (A B : HOD) (x : Ordinal) (lt : odef (ZFP A B) x) → odef (ZFP (ZPI2 A B) (ZPI1 A B)) (& < * (zπ2 lt) , * (zπ1 lt) >) pj2 A B x ab = ab-pair (pj02 A B x ab) (pj01 A B x ab) aZPI1 : (A B : HOD) {y : Ordinal} → odef (ZPI1 A B) y → odef A y aZPI1 A B {y} record { z = z ; az = az ; x=ψz = x=ψz } = subst (λ k → odef A k) (trans ( trans (sym &iso) (trans (sym (proj1 (pj12 A B az))) (sym &iso))) (sym x=ψz) ) ( zp1 az ) aZPI2 : (A B : HOD) {y : Ordinal} → odef (ZPI2 A B) y → odef B y aZPI2 A B {y} record { z = z ; az = az ; x=ψz = x=ψz } = subst (λ k → odef B k) (trans ( trans (sym &iso) (trans (sym (proj2 (pj12 A B az))) (sym &iso))) (sym x=ψz) ) ( zp2 az ) pj1 : (A B : HOD) (x : Ordinal) (lt : odef (ZFP (ZPI2 A B) (ZPI1 A B)) x) → odef (ZFP A B) (& < * (zπ2 lt) , * (zπ1 lt) >) pj1 A B _ (ab-pair ax by) = ab-pair (aZPI1 A B by) (aZPI2 A B ax) ZFPsym1 : (A B : HOD) → HODBijection (ZFP A B) (ZFP (ZPI2 A B) (ZPI1 A B)) ZFPsym1 A B = record { fun← = λ xy ab → & < * ( zπ2 ab) , * ( zπ1 ab) > ; fun→ = λ xy ab → & < * ( zπ2 ab) , * ( zπ1 ab) > ; funB = pj2 A B ; funA = pj1 A B ; fiso← = λ xy ab → pj00 A B ab ; fiso→ = λ xy ab → zp-iso ab } where pj10 : (A B : HOD) → {xy : Ordinal} → (ab : odef (ZFP (ZPI2 A B) (ZPI1 A B)) xy ) → & < * (zπ1 ab) , * (zπ2 ab) > ≡ & < * (zπ2 (pj1 A B xy ab)) , * (zπ1 (pj1 A B xy ab)) > pj10 A B {.(& < * _ , * _ >)} (ab-pair ax by ) = refl pj00 : (A B : HOD) → {xy : Ordinal} → (ab : odef (ZFP (ZPI2 A B) (ZPI1 A B)) xy ) → & < * (zπ2 (pj1 A B xy ab)) , * (zπ1 (pj1 A B xy ab)) > ≡ xy pj00 A B {xy} ab = trans (sym (pj10 A B ab)) (zp-iso {ZPI2 A B} {ZPI1 A B} {xy} ab) -- -- Bijection of (A x B) and (B x A) requires one element or axiom of choice -- ZFPsym : (A B : HOD) → {a b : Ordinal } → odef A a → odef B b → HODBijection (ZFP A B) (ZFP B A) ZFPsym A B aa bb = subst₂ ( λ j k → HODBijection (ZFP A B) (ZFP j k)) (ZPI2-iso A B aa) (ZPI1-iso A B bb) ( ZFPsym1 A B ) ⊆-ZFP : {A B : HOD} {X Y x y : HOD} → X ⊆ A → Y ⊆ B → ZFP X Y ⊆ ZFP A B ⊆-ZFP {A} {B} {X} {y} X<A Y<B (ab-pair xx yy) = ab-pair (X<A xx) (Y<B yy) record ZPC (A B C : HOD) ( cab : C ⊆ ZFP A B ) (x : Ordinal) : Set n where field a b : Ordinal aa : odef A a bb : odef B b c∋ab : odef C (& < * a , * b > ) x=ba : x ≡ & < * b , * a > ZPmirror : (A B C : HOD) → C ⊆ ZFP A B → HOD ZPmirror A B C cab = record { od = record { def = λ x → ZPC A B C cab x } ; odmax = osuc (& (Power (Union (B , A)))) ; <odmax = lemma0 } where lemma0 : {x : Ordinal } → ZPC A B C cab x → x o< osuc (& ( Power ( Union (B , A )) )) lemma0 {x} record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = c∋ab ; x=ba = x=ba } = subst (λ k → k o< _) (sym x=ba) lemma1 where lemma1 : & < * b , * a > o< osuc (& (Power (Union (B , A)))) lemma1 = ⊆→o≤ (ZFP<AB (subst (λ k → odef B k) (sym &iso) bb) (subst (λ k → odef A k) (sym &iso) aa) ) ZPmirror⊆ZFPBA : (A B C : HOD) → (cab : C ⊆ ZFP A B ) → ZPmirror A B C cab ⊆ ZFP B A ZPmirror⊆ZFPBA A B C cab {z} record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = c∋ab ; x=ba = x=ba } = subst (λ k → odef (ZFP B A) k) (sym x=ba) lemma2 where lemma2 : odef (ZFP B A) (& < * b , * a > ) lemma2 = ZFP→ (subst (λ k → odef B k ) (sym &iso) bb) (subst (λ k → odef A k ) (sym &iso) aa) ZPmirror-iso : (A B C : HOD) → (cab : C ⊆ ZFP A B ) → ( {x y : HOD} → C ∋ < x , y > → ZPmirror A B C cab ∋ < y , x > ) ∧ ( {x y : HOD} → ZPmirror A B C cab ∋ < y , x > → C ∋ < x , y > ) ZPmirror-iso A B C cab = ⟪ zs00 refl , zs01 ⟫ where zs00 : {x y : HOD} → {z : Ordinal} → z ≡ & < x , y > → odef C z → ZPmirror A B C cab ∋ < y , x > zs00 {x} {y} {z} eq cz with cab cz ... | ab-pair {a} {b} aa bb = record { a = _ ; b = _ ; aa = aa ; bb = bb ; c∋ab = cz ; x=ba = cong₂ (λ j k → & < j , k >) (sym (proj2 (prod-≡ (subst₂ (λ j k → j ≡ k) *iso *iso (cong (*) eq))))) (sym (proj1 (prod-≡ (subst₂ (λ j k → j ≡ k) *iso *iso (cong (*) eq))))) } zs01 : {x y : HOD} → ZPmirror A B C cab ∋ < y , x > → C ∋ < x , y > zs01 {x} {y} record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = c∋ab ; x=ba = x=ba } = subst (λ k → odef C k ) zs02 c∋ab where zs02 : & < * a , * b > ≡ & < x , y > zs02 = cong₂ (λ j k → & < j , k >) (sym (proj2 (prod-≡ (subst₂ (λ j k → j ≡ k) *iso *iso (cong (*) x=ba))))) (sym (proj1 (prod-≡ (subst₂ (λ j k → j ≡ k) *iso *iso (cong (*) x=ba))))) ZPmirror-rev : {A B C m : HOD} → {cab : C ⊆ ZFP A B } → ZPmirror A B C cab ≡ m → {m⊆Z : m ⊆ ZFP B A } → ZPmirror B A m m⊆Z ≡ C ZPmirror-rev {A} {B} {C} {m} {cab} eq {m⊆Z} = ==→o≡ record { eq→ = zs02 ; eq← = zs04 } where zs02 : {x : Ordinal} → ZPC B A m m⊆Z x → odef C x zs02 {x} record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = c∋ab ; x=ba = x=ba } with subst (λ k → odef k (& < * a , * b > )) (sym eq) c∋ab ... | record { a = b1 ; b = a1 ; aa = bb1 ; bb = aa1 ; c∋ab = c∋ab1 ; x=ba = x=ba1 } = subst (λ k → odef C k) zs03 c∋ab1 where a=a1 : * a ≡ * a1 a=a1 = proj1 (prod-≡ (subst₂ (λ j k → j ≡ k ) *iso *iso (cong (*) x=ba1))) b=b1 : * b ≡ * b1 b=b1 = proj2 (prod-≡ (subst₂ (λ j k → j ≡ k ) *iso *iso (cong (*) x=ba1))) zs03 : & < * b1 , * a1 > ≡ x zs03 = begin & < * b1 , * a1 > ≡⟨ cong₂ (λ j k → & < j , k >) (sym b=b1) (sym a=a1) ⟩ & < * b , * a > ≡⟨ sym x=ba ⟩ x ∎ where open ≡-Reasoning zs04 : {x : Ordinal} → odef C x → ZPC B A m m⊆Z x zs04 {x} cx with cab cx ... | ab-pair {a} {b} aa bb = record { a = b ; b = a ; aa = bb ; bb = aa ; c∋ab = subst (λ k → odef k (& < * b , * a >)) eq zs05 ; x=ba = refl } where zs05 : odef (ZPmirror A B C cab) (& < * b , * a >) zs05 = record { a = _ ; b = _ ; aa = aa ; bb = bb ; c∋ab = cx ; x=ba = refl } ZPmirror-⊆ : {A B C D : HOD} → (C⊆D : C ⊆ D) → {cab : C ⊆ ZFP A B } {dab : D ⊆ ZFP A B } → ZPmirror A B C cab ⊆ ZPmirror A B D dab ZPmirror-⊆ {A} {B} {C} {D} C⊆D {cab} {dab} {x} record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = c∋ab ; x=ba = x=ba } = record { a = _ ; b = _ ; aa = aa ; bb = bb ; c∋ab = C⊆D c∋ab ; x=ba = x=ba } ZPmirror-∩ : {A B C D : HOD} → {cdab : (C ∩ D) ⊆ ZFP A B } {cab : C ⊆ ZFP A B } {dab : D ⊆ ZFP A B } → ZPmirror A B (C ∩ D) cdab ≡ ZPmirror A B C cab ∩ ZPmirror A B D dab ZPmirror-∩ {A} {B} {C} {D} {cdab} {cab} {dab} = ==→o≡ record { eq→ = za06 ; eq← = za07 } where za06 : ZPmirror A B (C ∩ D) cdab ⊆ ( ZPmirror A B C cab ∩ ZPmirror A B D dab ) za06 {x} record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = c∋ab ; x=ba = x=ba } = ⟪ record { a = _ ; b = _ ; aa = aa ; bb = bb ; c∋ab = proj1 c∋ab ; x=ba = x=ba } , record { a = _ ; b = _ ; aa = aa ; bb = bb ; c∋ab = proj2 c∋ab ; x=ba = x=ba } ⟫ za07 : ( ZPmirror A B C cab ∩ ZPmirror A B D dab ) ⊆ ZPmirror A B (C ∩ D) cdab za07 {x} ⟪ record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = c∋ab1 ; x=ba = x=ba } , record { a = a' ; b = b' ; aa = aa' ; bb = bb' ; c∋ab = c∋ab2 ; x=ba = x=ba' } ⟫ = record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = ⟪ c∋ab1 , subst (λ k → odef D k) (sym zs02) c∋ab2 ⟫ ; x=ba = x=ba } where zs02 : & < * a , * b > ≡ & < * a' , * b' > zs02 = cong₂ (λ j k → & < j , k >) (sym (proj2 (prod-≡ (subst₂ (λ j k → j ≡ k) *iso *iso (cong (*) (trans (sym x=ba') x=ba)))))) (sym (proj1 (prod-≡ (subst₂ (λ j k → j ≡ k) *iso *iso (cong (*) (trans (sym x=ba') x=ba)))))) ZPmirror-neg : {A B C D : HOD} → {cdab : (C ＼ D) ⊆ ZFP A B } {cab : C ⊆ ZFP A B } {dab : D ⊆ ZFP A B } → ZPmirror A B (C ＼ D) cdab ≡ ZPmirror A B C cab ＼ ZPmirror A B D dab ZPmirror-neg {A} {B} {C} {D} {cdab} {cab} {dab} = ==→o≡ record { eq→ = za08 ; eq← = za10 } where za08 : {x : Ordinal} → ZPC A B (C ＼ D) cdab x → odef (ZPmirror A B C cab ＼ ZPmirror A B D dab) x za08 {x} record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = c∋ab ; x=ba = x=ba } = ⟪ record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = proj1 c∋ab ; x=ba = x=ba } , za09 ⟫ where za09 : ¬ odef (ZPmirror A B D dab) x za09 zd = ⊥-elim ( proj2 c∋ab (subst (λ k → odef D k) (sym zs02) (ZPC.c∋ab zd) ) ) where x=ba' = ZPC.x=ba zd zs02 : & < * a , * b > ≡ & < * (ZPC.a zd) , * (ZPC.b zd) > zs02 = cong₂ (λ j k → & < j , k >) (sym (proj2 (prod-≡ (subst₂ (λ j k → j ≡ k) *iso *iso (cong (*) (trans (sym x=ba' ) x=ba)))))) (sym (proj1 (prod-≡ (subst₂ (λ j k → j ≡ k) *iso *iso (cong (*) (trans (sym x=ba' ) x=ba)))))) za10 : {x : Ordinal} → odef (ZPmirror A B C cab ＼ ZPmirror A B D dab) x → ZPC A B (C ＼ D) cdab x za10 {x} ⟪ record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = c∋ab ; x=ba = x=ba } , neg ⟫ = record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = ⟪ c∋ab , za11 ⟫ ; x=ba = x=ba } where za11 : ¬ odef D (& < * a , * b >) za11 zd = ⊥-elim (neg record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = zd ; x=ba = x=ba }) ZPmirror-whole : {A B : HOD} → ZPmirror A B (ZFP A B) (λ x → x) ≡ ZFP B A ZPmirror-whole {A} {B} = ==→o≡ record { eq→ = za12 ; eq← = za13 } where za12 : {x : Ordinal} → ZPC A B (ZFP A B) (λ x₁ → x₁) x → ZFProduct B A x za12 {x} record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = c∋ab ; x=ba = x=ba } = subst (λ k → ZFProduct B A k) (sym x=ba) (ab-pair bb aa) za13 : {x : Ordinal} → ZFProduct B A x → ZPC A B (ZFP A B) (λ x₁ → x₁) x za13 {x} (ab-pair {b} {a} bb aa) = record { a = a ; b = b ; aa = aa ; bb = bb ; c∋ab = ab-pair aa bb ; x=ba = refl } ZPmirror-0 : {A B : HOD} {z : Ordinal } → {zab : * z ⊆ ZFP A B} → ZPmirror A B (* z) zab ≡ od∅ → z ≡ & od∅ ZPmirror-0 {A} {B} {z} {zab} eq = uf10 where uf10 : z ≡ & od∅ uf10 = trans (sym &iso) ( cong (&) (¬x∋y→x≡od∅ (λ {y} zy → uf11 zy ) )) where uf11 : {y : Ordinal } → odef (* z) y → ⊥ uf11 {y} zy = ⊥-elim ( ¬x<0 (subst (λ k → odef k (& < * (zπ2 pqy) , * (zπ1 pqy) >) ) eq uf12 ) ) where pqy : odef (ZFP A B) y pqy = zab zy uf14 : odef (* z) (& < * (zπ1 pqy) , * (zπ2 pqy) >) uf14 = subst (λ k → odef (* z) k ) (sym ( zp-iso pqy)) zy uf12 : odef (ZPmirror A B (* z) zab) (& < * (zπ2 pqy) , * (zπ1 pqy) > ) uf12 = record { a = _ ; b = _ ; aa = zp1 pqy ; bb = zp2 pqy ; c∋ab = uf14 ; x=ba = refl } ZFP∩ : {A B C : HOD} → ( ZFP (A ∩ B) C ≡ ZFP A C ∩ ZFP B C ) ∧ ( ZFP C (A ∩ B) ≡ ZFP C A ∩ ZFP C B ) proj1 (ZFP∩ {A} {B} {C} ) = ==→o≡ record { eq→ = zfp00 ; eq← = zfp01 } where zfp00 : {x : Ordinal} → ZFProduct (A ∩ B) C x → odef (ZFP A C ∩ ZFP B C) x zfp00 (ab-pair ⟪ pa , pb ⟫ qx) = ⟪ ab-pair pa qx , ab-pair pb qx ⟫ zfp01 : {x : Ordinal} → odef (ZFP A C ∩ ZFP B C) x → ZFProduct (A ∩ B) C x zfp01 {x} ⟪ p , q ⟫ = subst (λ k → ZFProduct (A ∩ B) C k) zfp07 ( ab-pair (zfp02 ⟪ p , q ⟫ ) (zfp04 q) ) where zfp05 : & < * (zπ1 p) , * (zπ2 p) > ≡ x zfp05 = zp-iso p zfp06 : & < * (zπ1 q) , * (zπ2 q) > ≡ x zfp06 = zp-iso q zfp07 : & < * (zπ1 p) , * (zπ2 q) > ≡ x zfp07 = trans (cong (λ k → & < k , * (zπ2 q) > ) (proj1 (prod-≡ (subst₂ _≡_ *iso *iso (cong (*) (trans zfp05 (sym (zfp06)))))))) zfp06 zfp02 : {x : Ordinal } → (acx : odef (ZFP A C ∩ ZFP B C) x) → odef (A ∩ B) (zπ1 (proj1 acx)) zfp02 {.(& < * _ , * _ >)} ⟪ ab-pair {a} {b} ax bx , bcx ⟫ = ⟪ ax , zfp03 bcx refl ⟫ where zfp03 : {x : Ordinal } → (bc : odef (ZFP B C) x) → x ≡ (& < * a , * b >) → odef B (zπ1 (ab-pair {A} {C} ax bx)) zfp03 (ab-pair {a1} {b1} x x₁) eq = subst (λ k → odef B k ) zfp08 x where zfp08 : a1 ≡ a zfp08 = subst₂ _≡_ &iso &iso (cong (&) (proj1 (prod-≡ (subst₂ _≡_ *iso *iso (cong (*) eq))))) zfp04 : {x : Ordinal } (acx : odef (ZFP B C) x )→ odef C (zπ2 acx) zfp04 (ab-pair x x₁) = x₁ proj2 (ZFP∩ {A} {B} {C} ) = ==→o≡ record { eq→ = zfp00 ; eq← = zfp01 } where zfp00 : {x : Ordinal} → ZFProduct C (A ∩ B) x → odef (ZFP C A ∩ ZFP C B) x zfp00 (ab-pair qx ⟪ pa , pb ⟫ ) = ⟪ ab-pair qx pa , ab-pair qx pb ⟫ zfp01 : {x : Ordinal} → odef (ZFP C A ∩ ZFP C B ) x → ZFProduct C (A ∩ B) x zfp01 {x} ⟪ p , q ⟫ = subst (λ k → ZFProduct C (A ∩ B) k) zfp07 ( ab-pair (zfp04 p) (zfp02 ⟪ p , q ⟫ ) ) where zfp05 : & < * (zπ1 p) , * (zπ2 p) > ≡ x zfp05 = zp-iso p zfp06 : & < * (zπ1 q) , * (zπ2 q) > ≡ x zfp06 = zp-iso q zfp07 : & < * (zπ1 p) , * (zπ2 q) > ≡ x zfp07 = trans (cong (λ k → & < * (zπ1 p) , k > ) (sym (proj2 (prod-≡ (subst₂ _≡_ *iso *iso (cong (*) (trans zfp05 (sym (zfp06))))))))) zfp05 zfp02 : {x : Ordinal } → (acx : odef (ZFP C A ∩ ZFP C B ) x) → odef (A ∩ B) (zπ2 (proj2 acx)) zfp02 {.(& < * _ , * _ >)} ⟪ bcx , ab-pair {b} {a} ax bx ⟫ = ⟪ zfp03 bcx refl , bx ⟫ where zfp03 : {x : Ordinal } → (bc : odef (ZFP C A ) x) → x ≡ (& < * b , * a >) → odef A (zπ2 (ab-pair {C} {B} ax bx )) zfp03 (ab-pair {b1} {a1} x x₁) eq = subst (λ k → odef A k ) zfp08 x₁ where zfp08 : a1 ≡ a zfp08 = subst₂ _≡_ &iso &iso (cong (&) (proj2 (prod-≡ (subst₂ _≡_ *iso *iso (cong (*) eq))))) zfp04 : {x : Ordinal } (acx : odef (ZFP C A ) x )→ odef C (zπ1 acx) zfp04 (ab-pair x x₁) = x open import BAlgebra O ZFP\Q : {P Q p : HOD} → (( ZFP P Q ＼ ZFP p Q ) ≡ ZFP (P ＼ p) Q ) ∧ (( ZFP P Q ＼ ZFP P p ) ≡ ZFP P (Q ＼ p) ) ZFP\Q {P} {Q} {p} = ⟪ ==→o≡ record { eq→ = ty70 ; eq← = ty71 } , ==→o≡ record { eq→ = ty73 ; eq← = ty75 } ⟫ where ty70 : {x : Ordinal } → odef ( ZFP P Q ＼ ZFP p Q ) x → odef (ZFP (P ＼ p) Q) x ty70 ⟪ ab-pair {a} {b} Pa pb , npq ⟫ = ab-pair ty72 pb where ty72 : odef (P ＼ p ) a ty72 = ⟪ Pa , (λ pa → npq (ab-pair pa pb ) ) ⟫ ty71 : {x : Ordinal } → odef (ZFP (P ＼ p) Q) x → odef ( ZFP P Q ＼ ZFP p Q ) x ty71 (ab-pair {a} {b} ⟪ Pa , npa ⟫ Qb) = ⟪ ab-pair Pa Qb , (λ pab → npa (subst (λ k → odef p k) (proj1 (zp-iso0 pab)) (zp1 pab)) ) ⟫ ty73 : {x : Ordinal } → odef ( ZFP P Q ＼ ZFP P p ) x → odef (ZFP P (Q ＼ p) ) x ty73 ⟪ ab-pair {a} {b} pa Qb , npq ⟫ = ab-pair pa ty72 where ty72 : odef (Q ＼ p ) b ty72 = ⟪ Qb , (λ qb → npq (ab-pair pa qb ) ) ⟫ ty75 : {x : Ordinal } → odef (ZFP P (Q ＼ p) ) x → odef ( ZFP P Q ＼ ZFP P p ) x ty75 (ab-pair {a} {b} Pa ⟪ Qb , nqb ⟫ ) = ⟪ ab-pair Pa Qb , (λ pab → nqb (subst (λ k → odef p k) (proj2 (zp-iso0 pab)) (zp2 pab)) ) ⟫