Mercurial > hg > Members > kono > Proof > ZF-in-agda
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MinSUP
| author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Fri, 30 Sep 2022 10:55:23 +0900 |
| parents | 1ec8c0cfc892 |
| children | d4839adf694d |
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{-# OPTIONS --allow-unsolved-metas #-} open import Level hiding ( suc ; zero ) open import Ordinals open import Relation.Binary open import Relation.Binary.Core open import Relation.Binary.PropositionalEquality import OD module zorn {n : Level } (O : Ordinals {n}) (_<_ : (x y : OD.HOD O ) → Set n ) (PO : IsStrictPartialOrder _≡_ _<_ ) where -- -- Zorn-lemma : { A : HOD } -- → o∅ o< & A -- → ( ( B : HOD) → (B⊆A : B ⊆ A) → IsTotalOrderSet B → SUP A B ) -- SUP condition -- → Maximal A -- open import zf open import logic -- open import partfunc {n} O open import Relation.Nullary open import Data.Empty import BAlgbra open import Data.Nat hiding ( _<_ ; _≤_ ) open import Data.Nat.Properties open import nat open inOrdinal O open OD O open OD.OD open ODAxiom odAxiom import OrdUtil import ODUtil open Ordinals.Ordinals O open Ordinals.IsOrdinals isOrdinal open Ordinals.IsNext isNext open OrdUtil O open ODUtil O import ODC open _∧_ open _∨_ open Bool open HOD -- -- Partial Order on HOD ( possibly limited in A ) -- _<<_ : (x y : Ordinal ) → Set n x << y = * x < * y _<=_ : (x y : Ordinal ) → Set n -- we can't use * x ≡ * y, it is Set (Level.suc n). Level (suc n) troubles Chain x <= y = (x ≡ y ) ∨ ( * x < * y ) POO : IsStrictPartialOrder _≡_ _<<_ POO = record { isEquivalence = record { refl = refl ; sym = sym ; trans = trans } ; trans = IsStrictPartialOrder.trans PO ; irrefl = λ x=y x<y → IsStrictPartialOrder.irrefl PO (cong (*) x=y) x<y ; <-resp-≈ = record { fst = λ {x} {y} {y1} y=y1 xy1 → subst (λ k → x << k ) y=y1 xy1 ; snd = λ {x} {x1} {y} x=x1 x1y → subst (λ k → k << x ) x=x1 x1y } } _≤_ : (x y : HOD) → Set (Level.suc n) x ≤ y = ( x ≡ y ) ∨ ( x < y ) ≤-ftrans : {x y z : HOD} → x ≤ y → y ≤ z → x ≤ z ≤-ftrans {x} {y} {z} (case1 refl ) (case1 refl ) = case1 refl ≤-ftrans {x} {y} {z} (case1 refl ) (case2 y<z) = case2 y<z ≤-ftrans {x} {_} {z} (case2 x<y ) (case1 refl ) = case2 x<y ≤-ftrans {x} {y} {z} (case2 x<y) (case2 y<z) = case2 ( IsStrictPartialOrder.trans PO x<y y<z ) <-ftrans : {x y z : Ordinal } → x <= y → y <= z → x <= z <-ftrans {x} {y} {z} (case1 refl ) (case1 refl ) = case1 refl <-ftrans {x} {y} {z} (case1 refl ) (case2 y<z) = case2 y<z <-ftrans {x} {_} {z} (case2 x<y ) (case1 refl ) = case2 x<y <-ftrans {x} {y} {z} (case2 x<y) (case2 y<z) = case2 ( IsStrictPartialOrder.trans PO x<y y<z ) <=to≤ : {x y : Ordinal } → x <= y → * x ≤ * y <=to≤ (case1 eq) = case1 (cong (*) eq) <=to≤ (case2 lt) = case2 lt ≤to<= : {x y : Ordinal } → * x ≤ * y → x <= y ≤to<= (case1 eq) = case1 ( subst₂ (λ j k → j ≡ k ) &iso &iso (cong (&) eq) ) ≤to<= (case2 lt) = case2 lt <-irr : {a b : HOD} → (a ≡ b ) ∨ (a < b ) → b < a → ⊥ <-irr {a} {b} (case1 a=b) b<a = IsStrictPartialOrder.irrefl PO (sym a=b) b<a <-irr {a} {b} (case2 a<b) b<a = IsStrictPartialOrder.irrefl PO refl (IsStrictPartialOrder.trans PO b<a a<b) ptrans = IsStrictPartialOrder.trans PO open _==_ open _⊆_ -- <-TransFinite : {A x : HOD} → {P : HOD → Set n} → x ∈ A -- → ({x : HOD} → A ∋ x → ({y : HOD} → A ∋ y → y < x → P y ) → P x) → P x -- <-TransFinite = ? -- -- Closure of ≤-monotonic function f has total order -- ≤-monotonic-f : (A : HOD) → ( Ordinal → Ordinal ) → Set (Level.suc n) ≤-monotonic-f A f = (x : Ordinal ) → odef A x → ( * x ≤ * (f x) ) ∧ odef A (f x ) data FClosure (A : HOD) (f : Ordinal → Ordinal ) (s : Ordinal) : Ordinal → Set n where init : {s1 : Ordinal } → odef A s → s ≡ s1 → FClosure A f s s1 fsuc : (x : Ordinal) ( p : FClosure A f s x ) → FClosure A f s (f x) A∋fc : {A : HOD} (s : Ordinal) {y : Ordinal } (f : Ordinal → Ordinal) (mf : ≤-monotonic-f A f) → (fcy : FClosure A f s y ) → odef A y A∋fc {A} s f mf (init as refl ) = as A∋fc {A} s f mf (fsuc y fcy) = proj2 (mf y ( A∋fc {A} s f mf fcy ) ) A∋fcs : {A : HOD} (s : Ordinal) {y : Ordinal } (f : Ordinal → Ordinal) (mf : ≤-monotonic-f A f) → (fcy : FClosure A f s y ) → odef A s A∋fcs {A} s f mf (init as refl) = as A∋fcs {A} s f mf (fsuc y fcy) = A∋fcs {A} s f mf fcy s≤fc : {A : HOD} (s : Ordinal ) {y : Ordinal } (f : Ordinal → Ordinal) (mf : ≤-monotonic-f A f) → (fcy : FClosure A f s y ) → * s ≤ * y s≤fc {A} s {.s} f mf (init x refl ) = case1 refl s≤fc {A} s {.(f x)} f mf (fsuc x fcy) with proj1 (mf x (A∋fc s f mf fcy ) ) ... | case1 x=fx = subst (λ k → * s ≤ * k ) (*≡*→≡ x=fx) ( s≤fc {A} s f mf fcy ) ... | case2 x<fx with s≤fc {A} s f mf fcy ... | case1 s≡x = case2 ( subst₂ (λ j k → j < k ) (sym s≡x) refl x<fx ) ... | case2 s<x = case2 ( IsStrictPartialOrder.trans PO s<x x<fx ) fcn : {A : HOD} (s : Ordinal) { x : Ordinal} {f : Ordinal → Ordinal} → (mf : ≤-monotonic-f A f) → FClosure A f s x → ℕ fcn s mf (init as refl) = zero fcn {A} s {x} {f} mf (fsuc y p) with proj1 (mf y (A∋fc s f mf p)) ... | case1 eq = fcn s mf p ... | case2 y<fy = suc (fcn s mf p ) fcn-inject : {A : HOD} (s : Ordinal) { x y : Ordinal} {f : Ordinal → Ordinal} → (mf : ≤-monotonic-f A f) → (cx : FClosure A f s x ) (cy : FClosure A f s y ) → fcn s mf cx ≡ fcn s mf cy → * x ≡ * y fcn-inject {A} s {x} {y} {f} mf cx cy eq = fc00 (fcn s mf cx) (fcn s mf cy) eq cx cy refl refl where fc06 : {y : Ordinal } { as : odef A s } (eq : s ≡ y ) { j : ℕ } → ¬ suc j ≡ fcn {A} s {y} {f} mf (init as eq ) fc06 {x} {y} refl {j} not = fc08 not where fc08 : {j : ℕ} → ¬ suc j ≡ 0 fc08 () fc07 : {x : Ordinal } (cx : FClosure A f s x ) → 0 ≡ fcn s mf cx → * s ≡ * x fc07 {x} (init as refl) eq = refl fc07 {.(f x)} (fsuc x cx) eq with proj1 (mf x (A∋fc s f mf cx ) ) ... | case1 x=fx = subst (λ k → * s ≡ k ) x=fx ( fc07 cx eq ) -- ... | case2 x<fx = ? fc00 : (i j : ℕ ) → i ≡ j → {x y : Ordinal } → (cx : FClosure A f s x ) (cy : FClosure A f s y ) → i ≡ fcn s mf cx → j ≡ fcn s mf cy → * x ≡ * y fc00 (suc i) (suc j) x cx (init x₃ x₄) x₁ x₂ = ⊥-elim ( fc06 x₄ x₂ ) fc00 (suc i) (suc j) x (init x₃ x₄) (fsuc x₅ cy) x₁ x₂ = ⊥-elim ( fc06 x₄ x₁ ) fc00 zero zero refl (init _ refl) (init x₁ refl) i=x i=y = refl fc00 zero zero refl (init as refl) (fsuc y cy) i=x i=y with proj1 (mf y (A∋fc s f mf cy ) ) ... | case1 y=fy = subst (λ k → * s ≡ k ) y=fy (fc07 cy i=y) -- ( fc00 zero zero refl (init as refl) cy i=x i=y ) fc00 zero zero refl (fsuc x cx) (init as refl) i=x i=y with proj1 (mf x (A∋fc s f mf cx ) ) ... | case1 x=fx = subst (λ k → k ≡ * s ) x=fx (sym (fc07 cx i=x)) -- ( fc00 zero zero refl cx (init as refl) i=x i=y ) fc00 zero zero refl (fsuc x cx) (fsuc y cy) i=x i=y with proj1 (mf x (A∋fc s f mf cx ) ) | proj1 (mf y (A∋fc s f mf cy ) ) ... | case1 x=fx | case1 y=fy = subst₂ (λ j k → j ≡ k ) x=fx y=fy ( fc00 zero zero refl cx cy i=x i=y ) fc00 (suc i) (suc j) i=j {.(f x)} {.(f y)} (fsuc x cx) (fsuc y cy) i=x j=y with proj1 (mf x (A∋fc s f mf cx ) ) | proj1 (mf y (A∋fc s f mf cy ) ) ... | case1 x=fx | case1 y=fy = subst₂ (λ j k → j ≡ k ) x=fx y=fy ( fc00 (suc i) (suc j) i=j cx cy i=x j=y ) ... | case1 x=fx | case2 y<fy = subst (λ k → k ≡ * (f y)) x=fx (fc02 x cx i=x) where fc02 : (x1 : Ordinal) → (cx1 : FClosure A f s x1 ) → suc i ≡ fcn s mf cx1 → * x1 ≡ * (f y) fc02 x1 (init x₁ x₂) x = ⊥-elim (fc06 x₂ x) fc02 .(f x1) (fsuc x1 cx1) i=x1 with proj1 (mf x1 (A∋fc s f mf cx1 ) ) ... | case1 eq = trans (sym eq) ( fc02 x1 cx1 i=x1 ) -- derefence while f x ≡ x ... | case2 lt = subst₂ (λ j k → * (f j) ≡ * (f k )) &iso &iso ( cong (λ k → * ( f (& k ))) fc04) where fc04 : * x1 ≡ * y fc04 = fc00 i j (cong pred i=j) cx1 cy (cong pred i=x1) (cong pred j=y) ... | case2 x<fx | case1 y=fy = subst (λ k → * (f x) ≡ k ) y=fy (fc03 y cy j=y) where fc03 : (y1 : Ordinal) → (cy1 : FClosure A f s y1 ) → suc j ≡ fcn s mf cy1 → * (f x) ≡ * y1 fc03 y1 (init x₁ x₂) x = ⊥-elim (fc06 x₂ x) fc03 .(f y1) (fsuc y1 cy1) j=y1 with proj1 (mf y1 (A∋fc s f mf cy1 ) ) ... | case1 eq = trans ( fc03 y1 cy1 j=y1 ) eq ... | case2 lt = subst₂ (λ j k → * (f j) ≡ * (f k )) &iso &iso ( cong (λ k → * ( f (& k ))) fc05) where fc05 : * x ≡ * y1 fc05 = fc00 i j (cong pred i=j) cx cy1 (cong pred i=x) (cong pred j=y1) ... | case2 x₁ | case2 x₂ = subst₂ (λ j k → * (f j) ≡ * (f k) ) &iso &iso (cong (λ k → * (f (& k))) (fc00 i j (cong pred i=j) cx cy (cong pred i=x) (cong pred j=y))) fcn-< : {A : HOD} (s : Ordinal ) { x y : Ordinal} {f : Ordinal → Ordinal} → (mf : ≤-monotonic-f A f) → (cx : FClosure A f s x ) (cy : FClosure A f s y ) → fcn s mf cx Data.Nat.< fcn s mf cy → * x < * y fcn-< {A} s {x} {y} {f} mf cx cy x<y = fc01 (fcn s mf cy) cx cy refl x<y where fc06 : {y : Ordinal } { as : odef A s } (eq : s ≡ y ) { j : ℕ } → ¬ suc j ≡ fcn {A} s {y} {f} mf (init as eq ) fc06 {x} {y} refl {j} not = fc08 not where fc08 : {j : ℕ} → ¬ suc j ≡ 0 fc08 () fc01 : (i : ℕ ) → {y : Ordinal } → (cx : FClosure A f s x ) (cy : FClosure A f s y ) → (i ≡ fcn s mf cy ) → fcn s mf cx Data.Nat.< i → * x < * y fc01 (suc i) cx (init x₁ x₂) x (s≤s x₃) = ⊥-elim (fc06 x₂ x) fc01 (suc i) {y} cx (fsuc y1 cy) i=y (s≤s x<i) with proj1 (mf y1 (A∋fc s f mf cy ) ) ... | case1 y=fy = subst (λ k → * x < k ) y=fy ( fc01 (suc i) {y1} cx cy i=y (s≤s x<i) ) ... | case2 y<fy with <-cmp (fcn s mf cx ) i ... | tri> ¬a ¬b c = ⊥-elim ( nat-≤> x<i c ) ... | tri≈ ¬a b ¬c = subst (λ k → k < * (f y1) ) (fcn-inject s mf cy cx (sym (trans b (cong pred i=y) ))) y<fy ... | tri< a ¬b ¬c = IsStrictPartialOrder.trans PO fc02 y<fy where fc03 : suc i ≡ suc (fcn s mf cy) → i ≡ fcn s mf cy fc03 eq = cong pred eq fc02 : * x < * y1 fc02 = fc01 i cx cy (fc03 i=y ) a fcn-cmp : {A : HOD} (s : Ordinal) { x y : Ordinal } (f : Ordinal → Ordinal) (mf : ≤-monotonic-f A f) → (cx : FClosure A f s x) → (cy : FClosure A f s y ) → Tri (* x < * y) (* x ≡ * y) (* y < * x ) fcn-cmp {A} s {x} {y} f mf cx cy with <-cmp ( fcn s mf cx ) (fcn s mf cy ) ... | tri< a ¬b ¬c = tri< fc11 (λ eq → <-irr (case1 (sym eq)) fc11) (λ lt → <-irr (case2 fc11) lt) where fc11 : * x < * y fc11 = fcn-< {A} s {x} {y} {f} mf cx cy a ... | tri≈ ¬a b ¬c = tri≈ (λ lt → <-irr (case1 (sym fc10)) lt) fc10 (λ lt → <-irr (case1 fc10) lt) where fc10 : * x ≡ * y fc10 = fcn-inject {A} s {x} {y} {f} mf cx cy b ... | tri> ¬a ¬b c = tri> (λ lt → <-irr (case2 fc12) lt) (λ eq → <-irr (case1 eq) fc12) fc12 where fc12 : * y < * x fc12 = fcn-< {A} s {y} {x} {f} mf cy cx c -- open import Relation.Binary.Properties.Poset as Poset IsTotalOrderSet : ( A : HOD ) → Set (Level.suc n) IsTotalOrderSet A = {a b : HOD} → odef A (& a) → odef A (& b) → Tri (a < b) (a ≡ b) (b < a ) ⊆-IsTotalOrderSet : { A B : HOD } → B ⊆ A → IsTotalOrderSet A → IsTotalOrderSet B ⊆-IsTotalOrderSet {A} {B} B⊆A T ax ay = T (incl B⊆A ax) (incl B⊆A ay) _⊆'_ : ( A B : HOD ) → Set n _⊆'_ A B = {x : Ordinal } → odef A x → odef B x -- -- inductive maxmum tree from x -- tree structure -- record HasPrev (A B : HOD) (x : Ordinal ) ( f : Ordinal → Ordinal ) : Set n where field ax : odef A x y : Ordinal ay : odef B y x=fy : x ≡ f y record IsSup (A B : HOD) {x : Ordinal } (xa : odef A x) : Set n where field x<sup : {y : Ordinal} → odef B y → (y ≡ x ) ∨ (y << x ) record SUP ( A B : HOD ) : Set (Level.suc n) where field sup : HOD as : A ∋ sup x<sup : {x : HOD} → B ∋ x → (x ≡ sup ) ∨ (x < sup ) -- B is Total, use positive -- -- sup and its fclosure is in a chain HOD -- chain HOD is sorted by sup as Ordinal and <-ordered -- whole chain is a union of separated Chain -- minimum index is sup of y not ϕ -- record ChainP (A : HOD ) ( f : Ordinal → Ordinal ) (mf : ≤-monotonic-f A f) {y : Ordinal} (ay : odef A y) (supf : Ordinal → Ordinal) (u : Ordinal) : Set n where field fcy<sup : {z : Ordinal } → FClosure A f y z → (z ≡ supf u) ∨ ( z << supf u ) order : {s z1 : Ordinal} → (lt : supf s o< supf u ) → FClosure A f (supf s ) z1 → (z1 ≡ supf u ) ∨ ( z1 << supf u ) supu=u : supf u ≡ u data UChain ( A : HOD ) ( f : Ordinal → Ordinal ) (mf : ≤-monotonic-f A f) {y : Ordinal } (ay : odef A y ) (supf : Ordinal → Ordinal) (x : Ordinal) : (z : Ordinal) → Set n where ch-init : {z : Ordinal } (fc : FClosure A f y z) → UChain A f mf ay supf x z ch-is-sup : (u : Ordinal) {z : Ordinal } (u<x : u o< x) ( is-sup : ChainP A f mf ay supf u ) ( fc : FClosure A f (supf u) z ) → UChain A f mf ay supf x z -- -- f (f ( ... (sup y))) f (f ( ... (sup z1))) -- / | / | -- / | / | -- sup y < sup z1 < sup z2 -- o< o< -- data UChain is total chain-total : (A : HOD ) ( f : Ordinal → Ordinal ) (mf : ≤-monotonic-f A f) {y : Ordinal} (ay : odef A y) (supf : Ordinal → Ordinal ) {s s1 a b : Ordinal } ( ca : UChain A f mf ay supf s a ) ( cb : UChain A f mf ay supf s1 b ) → Tri (* a < * b) (* a ≡ * b) (* b < * a ) chain-total A f mf {y} ay supf {xa} {xb} {a} {b} ca cb = ct-ind xa xb ca cb where ct-ind : (xa xb : Ordinal) → {a b : Ordinal} → UChain A f mf ay supf xa a → UChain A f mf ay supf xb b → Tri (* a < * b) (* a ≡ * b) (* b < * a) ct-ind xa xb {a} {b} (ch-init fca) (ch-init fcb) = fcn-cmp y f mf fca fcb ct-ind xa xb {a} {b} (ch-init fca) (ch-is-sup ub u≤x supb fcb) with ChainP.fcy<sup supb fca ... | case1 eq with s≤fc (supf ub) f mf fcb ... | case1 eq1 = tri≈ (λ lt → ⊥-elim (<-irr (case1 (sym ct00)) lt)) ct00 (λ lt → ⊥-elim (<-irr (case1 ct00) lt)) where ct00 : * a ≡ * b ct00 = trans (cong (*) eq) eq1 ... | case2 lt = tri< ct01 (λ eq → <-irr (case1 (sym eq)) ct01) (λ lt → <-irr (case2 ct01) lt) where ct01 : * a < * b ct01 = subst (λ k → * k < * b ) (sym eq) lt ct-ind xa xb {a} {b} (ch-init fca) (ch-is-sup ub u≤x supb fcb) | case2 lt = tri< ct01 (λ eq → <-irr (case1 (sym eq)) ct01) (λ lt → <-irr (case2 ct01) lt) where ct00 : * a < * (supf ub) ct00 = lt ct01 : * a < * b ct01 with s≤fc (supf ub) f mf fcb ... | case1 eq = subst (λ k → * a < k ) eq ct00 ... | case2 lt = IsStrictPartialOrder.trans POO ct00 lt ct-ind xa xb {a} {b} (ch-is-sup ua u≤x supa fca) (ch-init fcb) with ChainP.fcy<sup supa fcb ... | case1 eq with s≤fc (supf ua) f mf fca ... | case1 eq1 = tri≈ (λ lt → ⊥-elim (<-irr (case1 (sym ct00)) lt)) ct00 (λ lt → ⊥-elim (<-irr (case1 ct00) lt)) where ct00 : * a ≡ * b ct00 = sym (trans (cong (*) eq) eq1 ) ... | case2 lt = tri> (λ lt → <-irr (case2 ct01) lt) (λ eq → <-irr (case1 eq) ct01) ct01 where ct01 : * b < * a ct01 = subst (λ k → * k < * a ) (sym eq) lt ct-ind xa xb {a} {b} (ch-is-sup ua u≤x supa fca) (ch-init fcb) | case2 lt = tri> (λ lt → <-irr (case2 ct01) lt) (λ eq → <-irr (case1 eq) ct01) ct01 where ct00 : * b < * (supf ua) ct00 = lt ct01 : * b < * a ct01 with s≤fc (supf ua) f mf fca ... | case1 eq = subst (λ k → * b < k ) eq ct00 ... | case2 lt = IsStrictPartialOrder.trans POO ct00 lt ct-ind xa xb {a} {b} (ch-is-sup ua ua<x supa fca) (ch-is-sup ub ub<x supb fcb) with trio< ua ub ... | tri< a₁ ¬b ¬c with ChainP.order supb (subst₂ (λ j k → j o< k ) (sym (ChainP.supu=u supa )) (sym (ChainP.supu=u supb )) a₁) fca ... | case1 eq with s≤fc (supf ub) f mf fcb ... | case1 eq1 = tri≈ (λ lt → ⊥-elim (<-irr (case1 (sym ct00)) lt)) ct00 (λ lt → ⊥-elim (<-irr (case1 ct00) lt)) where ct00 : * a ≡ * b ct00 = trans (cong (*) eq) eq1 ... | case2 lt = tri< ct02 (λ eq → <-irr (case1 (sym eq)) ct02) (λ lt → <-irr (case2 ct02) lt) where ct02 : * a < * b ct02 = subst (λ k → * k < * b ) (sym eq) lt ct-ind xa xb {a} {b} (ch-is-sup ua ua<x supa fca) (ch-is-sup ub ub<x supb fcb) | tri< a₁ ¬b ¬c | case2 lt = tri< ct02 (λ eq → <-irr (case1 (sym eq)) ct02) (λ lt → <-irr (case2 ct02) lt) where ct03 : * a < * (supf ub) ct03 = lt ct02 : * a < * b ct02 with s≤fc (supf ub) f mf fcb ... | case1 eq = subst (λ k → * a < k ) eq ct03 ... | case2 lt = IsStrictPartialOrder.trans POO ct03 lt ct-ind xa xb {a} {b} (ch-is-sup ua ua<x supa fca) (ch-is-sup ub ub<x supb fcb) | tri≈ ¬a eq ¬c = fcn-cmp (supf ua) f mf fca (subst (λ k → FClosure A f k b ) (cong supf (sym eq)) fcb ) ct-ind xa xb {a} {b} (ch-is-sup ua ua<x supa fca) (ch-is-sup ub ub<x supb fcb) | tri> ¬a ¬b c with ChainP.order supa (subst₂ (λ j k → j o< k ) (sym (ChainP.supu=u supb )) (sym (ChainP.supu=u supa )) c) fcb ... | case1 eq with s≤fc (supf ua) f mf fca ... | case1 eq1 = tri≈ (λ lt → ⊥-elim (<-irr (case1 (sym ct00)) lt)) ct00 (λ lt → ⊥-elim (<-irr (case1 ct00) lt)) where ct00 : * a ≡ * b ct00 = sym (trans (cong (*) eq) eq1) ... | case2 lt = tri> (λ lt → <-irr (case2 ct02) lt) (λ eq → <-irr (case1 eq) ct02) ct02 where ct02 : * b < * a ct02 = subst (λ k → * k < * a ) (sym eq) lt ct-ind xa xb {a} {b} (ch-is-sup ua ua<x supa fca) (ch-is-sup ub ub<x supb fcb) | tri> ¬a ¬b c | case2 lt = tri> (λ lt → <-irr (case2 ct04) lt) (λ eq → <-irr (case1 (eq)) ct04) ct04 where ct05 : * b < * (supf ua) ct05 = lt ct04 : * b < * a ct04 with s≤fc (supf ua) f mf fca ... | case1 eq = subst (λ k → * b < k ) eq ct05 ... | case2 lt = IsStrictPartialOrder.trans POO ct05 lt ∈∧P→o< : {A : HOD } {y : Ordinal} → {P : Set n} → odef A y ∧ P → y o< & A ∈∧P→o< {A } {y} p = subst (λ k → k o< & A) &iso ( c<→o< (subst (λ k → odef A k ) (sym &iso ) (proj1 p ))) -- Union of supf z which o< x -- UnionCF : ( A : HOD ) ( f : Ordinal → Ordinal ) (mf : ≤-monotonic-f A f) {y : Ordinal } (ay : odef A y ) ( supf : Ordinal → Ordinal ) ( x : Ordinal ) → HOD UnionCF A f mf ay supf x = record { od = record { def = λ z → odef A z ∧ UChain A f mf ay supf x z } ; odmax = & A ; <odmax = λ {y} sy → ∈∧P→o< sy } supf-inject0 : {x y : Ordinal } {supf : Ordinal → Ordinal } → (supf-mono : {x y : Ordinal } → x o≤ y → supf x o≤ supf y ) → supf x o< supf y → x o< y supf-inject0 {x} {y} {supf} supf-mono sx<sy with trio< x y ... | tri< a ¬b ¬c = a ... | tri≈ ¬a refl ¬c = ⊥-elim ( o<¬≡ (cong supf refl) sx<sy ) ... | tri> ¬a ¬b y<x with osuc-≡< (supf-mono (o<→≤ y<x) ) ... | case1 eq = ⊥-elim ( o<¬≡ (sym eq) sx<sy ) ... | case2 lt = ⊥-elim ( o<> sx<sy lt ) record MinSUP ( A B : HOD ) : Set n where field sup : Ordinal asm : odef A sup x<sup : {x : Ordinal } → odef B x → (x ≡ sup ) ∨ (x << sup ) minsup : { sup1 : Ordinal } → odef A sup1 → ( {x : Ordinal } → odef B x → (x ≡ sup1 ) ∨ (x << sup1 )) → sup o≤ sup1 z09 : {b : Ordinal } { A : HOD } → odef A b → b o< & A z09 {b} {A} ab = subst (λ k → k o< & A) &iso ( c<→o< (subst (λ k → odef A k ) (sym &iso ) ab)) -- M→S : {A B : HOD} → MinSUP A B → SUP A B -- M→S {A} {B} ms = record { sup = MinSUP.sup ms ; as = MinSUP.asm ms ; x<sup = MinSUP.x<sup ms } record ZChain ( A : HOD ) ( f : Ordinal → Ordinal ) (mf : ≤-monotonic-f A f) {y : Ordinal} (ay : odef A y) ( z : Ordinal ) : Set (Level.suc n) where field supf : Ordinal → Ordinal asupf : {x : Ordinal } → odef A (supf x) chain : HOD chain = UnionCF A f mf ay supf z chain⊆A : chain ⊆' A chain⊆A = λ lt → proj1 lt field supf-mono : {x y : Ordinal } → x o≤ y → supf x o≤ supf y supf-< : {x y : Ordinal } → supf x o< supf y → supf x << supf y minsup : {x : Ordinal } → x o≤ z → MinSUP A (UnionCF A f mf ay supf x) sup : {x : Ordinal } → x o≤ z → SUP A (UnionCF A f mf ay supf x) sup {x} x≤z = ? -- M→S (minsup x≤z ) field sup=u : {b : Ordinal} → (ab : odef A b) → b o≤ z → IsSup A (UnionCF A f mf ay supf b) ab ∧ (¬ HasPrev A (UnionCF A f mf ay supf b) b f) → supf b ≡ b supf-is-sup : {x : Ordinal } → (x≤z : x o≤ z) → supf x ≡ & (SUP.sup (sup x≤z) ) csupf : {b : Ordinal } → supf b o< z → odef (UnionCF A f mf ay supf z) (supf b) -- supf z is not an element of this chain -- supf-max : {x : Ordinal } → z o< x → supf x ≡ supf z -- supf z may different from spuf pz x≤supfx : z o≤ supf z chain∋init : odef chain y chain∋init = ⟪ ay , ch-init (init ay refl) ⟫ f-next : {a : Ordinal} → odef chain a → odef chain (f a) f-next {a} ⟪ aa , ch-init fc ⟫ = ⟪ proj2 (mf a aa) , ch-init (fsuc _ fc) ⟫ f-next {a} ⟪ aa , ch-is-sup u u≤x is-sup fc ⟫ = ⟪ proj2 (mf a aa) , ch-is-sup u u≤x is-sup (fsuc _ fc ) ⟫ initial : {z : Ordinal } → odef chain z → * y ≤ * z initial {a} ⟪ aa , ua ⟫ with ua ... | ch-init fc = s≤fc y f mf fc ... | ch-is-sup u u≤x is-sup fc = ≤-ftrans (<=to≤ zc7) (s≤fc _ f mf fc) where zc7 : y <= supf u zc7 = ChainP.fcy<sup is-sup (init ay refl) f-total : IsTotalOrderSet chain f-total {a} {b} ca cb = subst₂ (λ j k → Tri (j < k) (j ≡ k) (k < j)) *iso *iso uz01 where uz01 : Tri (* (& a) < * (& b)) (* (& a) ≡ * (& b)) (* (& b) < * (& a) ) uz01 = chain-total A f mf ay supf ( (proj2 ca)) ( (proj2 cb)) supf-<= : {x y : Ordinal } → supf x <= supf y → supf x o≤ supf y supf-<= {x} {y} (case1 sx=sy) = o≤-refl0 sx=sy supf-<= {x} {y} (case2 sx<sy) with trio< (supf x) (supf y) ... | tri< a ¬b ¬c = o<→≤ a ... | tri≈ ¬a b ¬c = o≤-refl0 b ... | tri> ¬a ¬b c = ⊥-elim (<-irr (case2 sx<sy ) (supf-< c) ) supf-inject : {x y : Ordinal } → supf x o< supf y → x o< y supf-inject {x} {y} sx<sy with trio< x y ... | tri< a ¬b ¬c = a ... | tri≈ ¬a refl ¬c = ⊥-elim ( o<¬≡ (cong supf refl) sx<sy ) ... | tri> ¬a ¬b y<x with osuc-≡< (supf-mono (o<→≤ y<x) ) ... | case1 eq = ⊥-elim ( o<¬≡ (sym eq) sx<sy ) ... | case2 lt = ⊥-elim ( o<> sx<sy lt ) supf∈A : {b : Ordinal} → b o≤ z → odef A (supf b) supf∈A {b} b≤z = subst (λ k → odef A k ) (sym (supf-is-sup b≤z)) ( SUP.as ( sup b≤z ) ) -- supf-idem : {x : Ordinal } → supf x o≤ z → supf (supf x) ≡ supf x -- supf-idem {x} sx≤z = sup=u (supf∈A ?) sx≤z ? fcy<sup : {u w : Ordinal } → u o≤ z → FClosure A f y w → (w ≡ supf u ) ∨ ( w << supf u ) -- different from order because y o< supf fcy<sup {u} {w} u≤z fc with SUP.x<sup (sup u≤z) ⟪ subst (λ k → odef A k ) (sym &iso) (A∋fc {A} y f mf fc) , ch-init (subst (λ k → FClosure A f y k) (sym &iso) fc ) ⟫ ... | case1 eq = case1 (subst (λ k → k ≡ supf u ) &iso (trans (cong (&) eq) (sym (supf-is-sup u≤z ) ) )) ... | case2 lt = case2 (subst (λ k → * w < k ) (subst (λ k → k ≡ _ ) *iso (cong (*) (sym (supf-is-sup u≤z ))) ) lt ) -- ordering is not proved here but in ZChain1 record ZChain1 ( A : HOD ) ( f : Ordinal → Ordinal ) (mf : ≤-monotonic-f A f) {y : Ordinal} (ay : odef A y) (zc : ZChain A f mf ay (& A)) ( z : Ordinal ) : Set (Level.suc n) where supf = ZChain.supf zc field is-max : {a b : Ordinal } → (ca : odef (UnionCF A f mf ay supf z) a ) → b o< z → (ab : odef A b) → HasPrev A (UnionCF A f mf ay supf z) b f ∨ IsSup A (UnionCF A f mf ay supf z) ab → * a < * b → odef ((UnionCF A f mf ay supf z)) b record Maximal ( A : HOD ) : Set (Level.suc n) where field maximal : HOD as : A ∋ maximal ¬maximal<x : {x : HOD} → A ∋ x → ¬ maximal < x -- A is Partial, use negative init-uchain : (A : HOD) ( f : Ordinal → Ordinal ) (mf : ≤-monotonic-f A f) {y : Ordinal } → (ay : odef A y ) { supf : Ordinal → Ordinal } { x : Ordinal } → odef (UnionCF A f mf ay supf x) y init-uchain A f mf ay = ⟪ ay , ch-init (init ay refl) ⟫ Zorn-lemma : { A : HOD } → o∅ o< & A → ( ( B : HOD) → (B⊆A : B ⊆' A) → IsTotalOrderSet B → SUP A B ) -- SUP condition → Maximal A Zorn-lemma {A} 0<A supP = zorn00 where <-irr0 : {a b : HOD} → A ∋ a → A ∋ b → (a ≡ b ) ∨ (a < b ) → b < a → ⊥ <-irr0 {a} {b} A∋a A∋b = <-irr z07 : {y : Ordinal} {A : HOD } → {P : Set n} → odef A y ∧ P → y o< & A z07 {y} {A} p = subst (λ k → k o< & A) &iso ( c<→o< (subst (λ k → odef A k ) (sym &iso ) (proj1 p ))) s : HOD s = ODC.minimal O A (λ eq → ¬x<0 ( subst (λ k → o∅ o< k ) (=od∅→≡o∅ eq) 0<A )) as : A ∋ * ( & s ) as = subst (λ k → odef A (& k) ) (sym *iso) ( ODC.x∋minimal O A (λ eq → ¬x<0 ( subst (λ k → o∅ o< k ) (=od∅→≡o∅ eq) 0<A )) ) as0 : odef A (& s ) as0 = subst (λ k → odef A k ) &iso as s<A : & s o< & A s<A = c<→o< (subst (λ k → odef A (& k) ) *iso as ) HasMaximal : HOD HasMaximal = record { od = record { def = λ x → odef A x ∧ ( (m : Ordinal) → odef A m → ¬ (* x < * m)) } ; odmax = & A ; <odmax = z07 } no-maximum : HasMaximal =h= od∅ → (x : Ordinal) → odef A x ∧ ((m : Ordinal) → odef A m → odef A x ∧ (¬ (* x < * m) )) → ⊥ no-maximum nomx x P = ¬x<0 (eq→ nomx {x} ⟪ proj1 P , (λ m ma p → proj2 ( proj2 P m ma ) p ) ⟫ ) Gtx : { x : HOD} → A ∋ x → HOD Gtx {x} ax = record { od = record { def = λ y → odef A y ∧ (x < (* y)) } ; odmax = & A ; <odmax = z07 } z08 : ¬ Maximal A → HasMaximal =h= od∅ z08 nmx = record { eq→ = λ {x} lt → ⊥-elim ( nmx record {maximal = * x ; as = subst (λ k → odef A k) (sym &iso) (proj1 lt) ; ¬maximal<x = λ {y} ay → subst (λ k → ¬ (* x < k)) *iso (proj2 lt (& y) ay) } ) ; eq← = λ {y} lt → ⊥-elim ( ¬x<0 lt )} x-is-maximal : ¬ Maximal A → {x : Ordinal} → (ax : odef A x) → & (Gtx (subst (λ k → odef A k ) (sym &iso) ax)) ≡ o∅ → (m : Ordinal) → odef A m → odef A x ∧ (¬ (* x < * m)) x-is-maximal nmx {x} ax nogt m am = ⟪ subst (λ k → odef A k) &iso (subst (λ k → odef A k ) (sym &iso) ax) , ¬x<m ⟫ where ¬x<m : ¬ (* x < * m) ¬x<m x<m = ∅< {Gtx (subst (λ k → odef A k ) (sym &iso) ax)} {* m} ⟪ subst (λ k → odef A k) (sym &iso) am , subst (λ k → * x < k ) (cong (*) (sym &iso)) x<m ⟫ (≡o∅→=od∅ nogt) minsupP : ( B : HOD) → (B⊆A : B ⊆' A) → IsTotalOrderSet B → MinSUP A B minsupP B B⊆A total = m02 where xsup : (sup : Ordinal ) → Set n xsup sup = {w : Ordinal } → odef B w → (w ≡ sup ) ∨ (w << sup ) ∀-imply-or : {A : Ordinal → Set n } {B : Set n } → ((x : Ordinal ) → A x ∨ B) → ((x : Ordinal ) → A x) ∨ B ∀-imply-or {A} {B} ∀AB with ODC.p∨¬p O ((x : Ordinal ) → A x) -- LEM ∀-imply-or {A} {B} ∀AB | case1 t = case1 t ∀-imply-or {A} {B} ∀AB | case2 x = case2 (lemma (λ not → x not )) where lemma : ¬ ((x : Ordinal ) → A x) → B lemma not with ODC.p∨¬p O B lemma not | case1 b = b lemma not | case2 ¬b = ⊥-elim (not (λ x → dont-orb (∀AB x) ¬b )) m00 : (x : Ordinal ) → ( ( z : Ordinal) → z o< x → ¬ (odef A z ∧ xsup z) ) ∨ MinSUP A B m00 x = TransFinite0 ind x where ind : (x : Ordinal) → ((z : Ordinal) → z o< x → ( ( w : Ordinal) → w o< z → ¬ (odef A w ∧ xsup w )) ∨ MinSUP A B) → ( ( w : Ordinal) → w o< x → ¬ (odef A w ∧ xsup w) ) ∨ MinSUP A B ind x prev = ∀-imply-or m01 where m01 : (z : Ordinal) → (z o< x → ¬ (odef A z ∧ xsup z)) ∨ MinSUP A B m01 z with trio< z x ... | tri≈ ¬a b ¬c = case1 ( λ lt → ⊥-elim ( ¬a lt ) ) ... | tri> ¬a ¬b c = case1 ( λ lt → ⊥-elim ( ¬a lt ) ) ... | tri< a ¬b ¬c with prev z a ... | case2 mins = case2 mins ... | case1 not with ODC.p∨¬p O (odef A z ∧ xsup z) ... | case1 mins = case2 record { sup = z ; asm = proj1 mins ; x<sup = proj2 mins ; minsup = m04 } where m04 : {sup1 : Ordinal} → odef A sup1 → ({w : Ordinal} → odef B w → (w ≡ sup1) ∨ (w << sup1)) → z o≤ sup1 m04 {s} as lt with trio< z s ... | tri< a ¬b ¬c = o<→≤ a ... | tri≈ ¬a b ¬c = o≤-refl0 b ... | tri> ¬a ¬b s<z = ⊥-elim ( not s s<z ⟪ as , lt ⟫ ) ... | case2 notz = case1 (λ _ → notz ) m03 : ¬ ((z : Ordinal) → z o< & A → ¬ odef A z ∧ xsup z) m03 not = ⊥-elim ( not s1 (z09 (SUP.as S)) ⟪ SUP.as S , m05 ⟫ ) where S : SUP A B S = supP B B⊆A total s1 = & (SUP.sup S) m05 : {w : Ordinal } → odef B w → (w ≡ s1 ) ∨ (w << s1 ) m05 {w} bw with SUP.x<sup S {* w} (subst (λ k → odef B k) (sym &iso) bw ) ... | case1 eq = case1 ( subst₂ (λ j k → j ≡ k ) &iso refl (cong (&) eq) ) ... | case2 lt = case2 ( subst (λ k → _ < k ) (sym *iso) lt ) m02 : MinSUP A B m02 = dont-or (m00 (& A)) m03 -- Uncountable ascending chain by axiom of choice cf : ¬ Maximal A → Ordinal → Ordinal cf nmx x with ODC.∋-p O A (* x) ... | no _ = o∅ ... | yes ax with is-o∅ (& ( Gtx ax )) ... | yes nogt = -- no larger element, so it is maximal ⊥-elim (no-maximum (z08 nmx) x ⟪ subst (λ k → odef A k) &iso ax , x-is-maximal nmx (subst (λ k → odef A k ) &iso ax) nogt ⟫ ) ... | no not = & (ODC.minimal O (Gtx ax) (λ eq → not (=od∅→≡o∅ eq))) is-cf : (nmx : ¬ Maximal A ) → {x : Ordinal} → odef A x → odef A (cf nmx x) ∧ ( * x < * (cf nmx x) ) is-cf nmx {x} ax with ODC.∋-p O A (* x) ... | no not = ⊥-elim ( not (subst (λ k → odef A k ) (sym &iso) ax )) ... | yes ax with is-o∅ (& ( Gtx ax )) ... | yes nogt = ⊥-elim (no-maximum (z08 nmx) x ⟪ subst (λ k → odef A k) &iso ax , x-is-maximal nmx (subst (λ k → odef A k ) &iso ax) nogt ⟫ ) ... | no not = ODC.x∋minimal O (Gtx ax) (λ eq → not (=od∅→≡o∅ eq)) --- --- infintie ascention sequence of f --- cf-is-<-monotonic : (nmx : ¬ Maximal A ) → (x : Ordinal) → odef A x → ( * x < * (cf nmx x) ) ∧ odef A (cf nmx x ) cf-is-<-monotonic nmx x ax = ⟪ proj2 (is-cf nmx ax ) , proj1 (is-cf nmx ax ) ⟫ cf-is-≤-monotonic : (nmx : ¬ Maximal A ) → ≤-monotonic-f A ( cf nmx ) cf-is-≤-monotonic nmx x ax = ⟪ case2 (proj1 ( cf-is-<-monotonic nmx x ax )) , proj2 ( cf-is-<-monotonic nmx x ax ) ⟫ chain-mono : ( f : Ordinal → Ordinal ) → (mf : ≤-monotonic-f A f ) {y : Ordinal} (ay : odef A y) (supf : Ordinal → Ordinal ) {a b c : Ordinal} → a o≤ b → odef (UnionCF A f mf ay supf a) c → odef (UnionCF A f mf ay supf b) c chain-mono f mf ay supf {a} {b} {c} a≤b ⟪ ua , ch-init fc ⟫ = ⟪ ua , ch-init fc ⟫ chain-mono f mf ay supf {a} {b} {c} a≤b ⟪ uaa , ch-is-sup ua ua<x is-sup fc ⟫ = ⟪ uaa , ch-is-sup ua (ordtrans<-≤ ua<x a≤b ) is-sup fc ⟫ sp0 : ( f : Ordinal → Ordinal ) → (mf : ≤-monotonic-f A f ) {x y : Ordinal} (ay : odef A y) (zc : ZChain A f mf ay x ) → SUP A (ZChain.chain zc) sp0 f mf ay zc = supP (ZChain.chain zc) (ZChain.chain⊆A zc) ztotal where ztotal : IsTotalOrderSet (ZChain.chain zc) ztotal {a} {b} ca cb = subst₂ (λ j k → Tri (j < k) (j ≡ k) (k < j)) *iso *iso uz01 where uz01 : Tri (* (& a) < * (& b)) (* (& a) ≡ * (& b)) (* (& b) < * (& a) ) uz01 = chain-total A f mf ay (ZChain.supf zc) ( (proj2 ca)) ( (proj2 cb)) -- -- Second TransFinite Pass for maximality -- SZ1 : ( f : Ordinal → Ordinal ) (mf : ≤-monotonic-f A f) {init : Ordinal} (ay : odef A init) (zc : ZChain A f mf ay (& A)) (x : Ordinal) → ZChain1 A f mf ay zc x SZ1 f mf {y} ay zc x = TransFinite { λ x → ZChain1 A f mf ay zc x } zc1 x where chain-mono1 : {a b c : Ordinal} → a o≤ b → odef (UnionCF A f mf ay (ZChain.supf zc) a) c → odef (UnionCF A f mf ay (ZChain.supf zc) b) c chain-mono1 {a} {b} {c} a≤b = chain-mono f mf ay (ZChain.supf zc) a≤b is-max-hp : (x : Ordinal) {a : Ordinal} {b : Ordinal} → odef (UnionCF A f mf ay (ZChain.supf zc) x) a → b o< x → (ab : odef A b) → HasPrev A (UnionCF A f mf ay (ZChain.supf zc) x) b f → * a < * b → odef (UnionCF A f mf ay (ZChain.supf zc) x) b is-max-hp x {a} {b} ua b<x ab has-prev a<b with HasPrev.ay has-prev ... | ⟪ ab0 , ch-init fc ⟫ = ⟪ ab , ch-init ( subst (λ k → FClosure A f y k) (sym (HasPrev.x=fy has-prev)) (fsuc _ fc )) ⟫ ... | ⟪ ab0 , ch-is-sup u u≤x is-sup fc ⟫ = ⟪ ab , subst (λ k → UChain A f mf ay (ZChain.supf zc) x k ) (sym (HasPrev.x=fy has-prev)) ( ch-is-sup u u≤x is-sup (fsuc _ fc)) ⟫ supf = ZChain.supf zc csupf-fc : {b s z1 : Ordinal} → b o≤ & A → supf s o< supf b → FClosure A f (supf s) z1 → UnionCF A f mf ay supf b ∋ * z1 csupf-fc {b} {s} {z1} b≤z ss<sb (init x refl ) = subst (λ k → odef (UnionCF A f mf ay supf b) k ) (sym &iso) zc05 where s<b : s o< b s<b = ZChain.supf-inject zc ss<sb s≤<z : s o≤ & A s≤<z = ordtrans s<b b≤z zc04 : odef (UnionCF A f mf ay supf (& A)) (supf s) zc04 = ZChain.csupf zc (z09 (ZChain.asupf zc)) zc05 : odef (UnionCF A f mf ay supf b) (supf s) zc05 with zc04 ... | ⟪ as , ch-init fc ⟫ = ⟪ as , ch-init fc ⟫ ... | ⟪ as , ch-is-sup u u<x is-sup fc ⟫ = ⟪ as , ch-is-sup u (zc09 zc08) is-sup fc ⟫ where zc07 : FClosure A f (supf u) (supf s) -- supf u ≤ supf s → supf u o≤ supf s zc07 = fc zc06 : supf u ≡ u zc06 = ChainP.supu=u is-sup zc08 : u o≤ supf s zc08 = subst (λ k → k o≤ supf s) zc06 (ZChain.supf-<= zc (≤to<= ( s≤fc _ f mf fc ))) zc09 : u o≤ supf s → u o< b zc09 u≤s with osuc-≡< u≤s ... | case1 u=ss = ZChain.supf-inject zc (subst (λ k → k o< supf b) (sym (trans zc06 u=ss)) ss<sb ) ... | case2 u<ss = ordtrans (ZChain.supf-inject zc (subst (λ k → k o< supf s) (sym zc06) u<ss)) s<b csupf-fc {b} {s} {z1} b<z ss≤sb (fsuc x fc) = subst (λ k → odef (UnionCF A f mf ay supf b) k ) (sym &iso) zc04 where zc04 : odef (UnionCF A f mf ay supf b) (f x) zc04 with subst (λ k → odef (UnionCF A f mf ay supf b) k ) &iso (csupf-fc b<z ss≤sb fc ) ... | ⟪ as , ch-init fc ⟫ = ⟪ proj2 (mf _ as) , ch-init (fsuc _ fc) ⟫ ... | ⟪ as , ch-is-sup u u≤x is-sup fc ⟫ = ⟪ proj2 (mf _ as) , ch-is-sup u u≤x is-sup (fsuc _ fc) ⟫ order : {b s z1 : Ordinal} → b o< & A → supf s o< supf b → FClosure A f (supf s) z1 → (z1 ≡ supf b) ∨ (z1 << supf b) order {b} {s} {z1} b<z ss<sb fc = zc04 where zc00 : ( * z1 ≡ SUP.sup (ZChain.sup zc (o<→≤ b<z) )) ∨ ( * z1 < SUP.sup ( ZChain.sup zc (o<→≤ b<z) ) ) zc00 = SUP.x<sup (ZChain.sup zc (o<→≤ b<z) ) (csupf-fc (o<→≤ b<z) ss<sb fc ) -- supf (supf b) ≡ supf b zc04 : (z1 ≡ supf b) ∨ (z1 << supf b) zc04 with zc00 ... | case1 eq = case1 (subst₂ (λ j k → j ≡ k ) &iso (sym (ZChain.supf-is-sup zc (o<→≤ b<z)) ) (cong (&) eq) ) ... | case2 lt = case2 (subst₂ (λ j k → j < k ) refl (subst₂ (λ j k → j ≡ k ) *iso refl (cong (*) (sym (ZChain.supf-is-sup zc (o<→≤ b<z) ) ))) lt ) zc1 : (x : Ordinal) → ((y₁ : Ordinal) → y₁ o< x → ZChain1 A f mf ay zc y₁) → ZChain1 A f mf ay zc x zc1 x prev with Oprev-p x ... | yes op = record { is-max = is-max } where px = Oprev.oprev op zc-b<x : {b : Ordinal } → b o< x → b o< osuc px zc-b<x {b} lt = subst (λ k → b o< k ) (sym (Oprev.oprev=x op)) lt is-max : {a : Ordinal} {b : Ordinal} → odef (UnionCF A f mf ay (ZChain.supf zc) x) a → b o< x → (ab : odef A b) → HasPrev A (UnionCF A f mf ay supf x) b f ∨ IsSup A (UnionCF A f mf ay supf x) ab → * a < * b → odef (UnionCF A f mf ay supf x) b is-max {a} {b} ua b<x ab P a<b with ODC.or-exclude O P is-max {a} {b} ua b<x ab P a<b | case1 has-prev = is-max-hp x {a} {b} ua b<x ab has-prev a<b is-max {a} {b} ua b<x ab P a<b | case2 is-sup = ⟪ ab , ch-is-sup b b<x m06 (subst (λ k → FClosure A f k b) (sym m05) (init ab refl)) ⟫ where b<A : b o< & A b<A = z09 ab m04 : ¬ HasPrev A (UnionCF A f mf ay supf b) b f m04 nhp = proj1 is-sup ( record { ax = HasPrev.ax nhp ; y = HasPrev.y nhp ; ay = chain-mono1 (o<→≤ b<x) (HasPrev.ay nhp) ; x=fy = HasPrev.x=fy nhp } ) m05 : ZChain.supf zc b ≡ b m05 = ZChain.sup=u zc ab (o<→≤ (z09 ab) ) ⟪ record { x<sup = λ {z} uz → IsSup.x<sup (proj2 is-sup) (chain-mono1 (o<→≤ b<x) uz ) } , m04 ⟫ m08 : {z : Ordinal} → (fcz : FClosure A f y z ) → z <= ZChain.supf zc b m08 {z} fcz = ZChain.fcy<sup zc (o<→≤ b<A) fcz m09 : {s z1 : Ordinal} → ZChain.supf zc s o< ZChain.supf zc b → FClosure A f (ZChain.supf zc s) z1 → z1 <= ZChain.supf zc b m09 {s} {z} s<b fcz = order b<A s<b fcz m06 : ChainP A f mf ay supf b m06 = record { fcy<sup = m08 ; order = m09 ; supu=u = m05 } ... | no lim = record { is-max = is-max } where is-max : {a : Ordinal} {b : Ordinal} → odef (UnionCF A f mf ay supf x) a → b o< x → (ab : odef A b) → HasPrev A (UnionCF A f mf ay supf x) b f ∨ IsSup A (UnionCF A f mf ay supf x) ab → * a < * b → odef (UnionCF A f mf ay supf x) b is-max {a} {b} ua b<x ab P a<b with ODC.or-exclude O P is-max {a} {b} ua b<x ab P a<b | case1 has-prev = is-max-hp x {a} {b} ua b<x ab has-prev a<b is-max {a} {b} ua b<x ab P a<b | case2 is-sup with IsSup.x<sup (proj2 is-sup) (init-uchain A f mf ay ) ... | case1 b=y = ⟪ subst (λ k → odef A k ) b=y ay , ch-init (subst (λ k → FClosure A f y k ) b=y (init ay refl )) ⟫ ... | case2 y<b = chain-mono1 (osucc b<x) ⟪ ab , ch-is-sup b <-osuc m06 (subst (λ k → FClosure A f k b) (sym m05) (init ab refl)) ⟫ where m09 : b o< & A m09 = subst (λ k → k o< & A) &iso ( c<→o< (subst (λ k → odef A k ) (sym &iso ) ab)) m07 : {z : Ordinal} → FClosure A f y z → z <= ZChain.supf zc b m07 {z} fc = ZChain.fcy<sup zc (o<→≤ m09) fc m08 : {s z1 : Ordinal} → ZChain.supf zc s o< ZChain.supf zc b → FClosure A f (ZChain.supf zc s) z1 → z1 <= ZChain.supf zc b m08 {s} {z1} s<b fc = order m09 s<b fc m04 : ¬ HasPrev A (UnionCF A f mf ay supf b) b f m04 nhp = proj1 is-sup ( record { ax = HasPrev.ax nhp ; y = HasPrev.y nhp ; ay = chain-mono1 (o<→≤ b<x) (HasPrev.ay nhp) ; x=fy = HasPrev.x=fy nhp } ) m05 : ZChain.supf zc b ≡ b m05 = ZChain.sup=u zc ab (o<→≤ m09) ⟪ record { x<sup = λ lt → IsSup.x<sup (proj2 is-sup) (chain-mono1 (o<→≤ b<x) lt )} , m04 ⟫ -- ZChain on x m06 : ChainP A f mf ay supf b m06 = record { fcy<sup = m07 ; order = m08 ; supu=u = m05 } --- --- the maximum chain has fix point of any ≤-monotonic function --- fixpoint : ( f : Ordinal → Ordinal ) → (mf : ≤-monotonic-f A f ) (zc : ZChain A f mf as0 (& A) ) → f (& (SUP.sup (sp0 f mf as0 zc ))) ≡ & (SUP.sup (sp0 f mf as0 zc )) fixpoint f mf zc = z14 where chain = ZChain.chain zc sp1 = sp0 f mf as0 zc z10 : {a b : Ordinal } → (ca : odef chain a ) → b o< & A → (ab : odef A b ) → HasPrev A chain b f ∨ IsSup A chain {b} ab -- (supO chain (ZChain.chain⊆A zc) (ZChain.f-total zc) ≡ b ) → * a < * b → odef chain b z10 = ZChain1.is-max (SZ1 f mf as0 zc (& A) ) z11 : & (SUP.sup sp1) o< & A z11 = c<→o< ( SUP.as sp1) z12 : odef chain (& (SUP.sup sp1)) z12 with o≡? (& s) (& (SUP.sup sp1)) ... | yes eq = subst (λ k → odef chain k) eq ( ZChain.chain∋init zc ) ... | no ne = z10 {& s} {& (SUP.sup sp1)} ( ZChain.chain∋init zc ) z11 (SUP.as sp1) (case2 z19 ) z13 where z13 : * (& s) < * (& (SUP.sup sp1)) z13 with SUP.x<sup sp1 ( ZChain.chain∋init zc ) ... | case1 eq = ⊥-elim ( ne (cong (&) eq) ) ... | case2 lt = subst₂ (λ j k → j < k ) (sym *iso) (sym *iso) lt z19 : IsSup A chain {& (SUP.sup sp1)} (SUP.as sp1) z19 = record { x<sup = z20 } where z20 : {y : Ordinal} → odef chain y → (y ≡ & (SUP.sup sp1)) ∨ (y << & (SUP.sup sp1)) z20 {y} zy with SUP.x<sup sp1 (subst (λ k → odef chain k ) (sym &iso) zy) ... | case1 y=p = case1 (subst (λ k → k ≡ _ ) &iso ( cong (&) y=p )) ... | case2 y<p = case2 (subst (λ k → * y < k ) (sym *iso) y<p ) -- λ {y} zy → subst (λ k → (y ≡ & k ) ∨ (y << & k)) ? (SUP.x<sup sp1 ? ) } ztotal : IsTotalOrderSet (ZChain.chain zc) ztotal {a} {b} ca cb = subst₂ (λ j k → Tri (j < k) (j ≡ k) (k < j)) *iso *iso uz01 where uz01 : Tri (* (& a) < * (& b)) (* (& a) ≡ * (& b)) (* (& b) < * (& a) ) uz01 = chain-total A f mf as0 (ZChain.supf zc) ( (proj2 ca)) ( (proj2 cb)) z14 : f (& (SUP.sup (sp0 f mf as0 zc ))) ≡ & (SUP.sup (sp0 f mf as0 zc )) z14 with ztotal (subst (λ k → odef chain k) (sym &iso) (ZChain.f-next zc z12 )) z12 ... | tri< a ¬b ¬c = ⊥-elim z16 where z16 : ⊥ z16 with proj1 (mf (& ( SUP.sup sp1)) ( SUP.as sp1 )) ... | case1 eq = ⊥-elim (¬b (subst₂ (λ j k → j ≡ k ) refl *iso (sym eq) )) ... | case2 lt = ⊥-elim (¬c (subst₂ (λ j k → k < j ) refl *iso lt )) ... | tri≈ ¬a b ¬c = subst ( λ k → k ≡ & (SUP.sup sp1) ) &iso ( cong (&) b ) ... | tri> ¬a ¬b c = ⊥-elim z17 where z15 : (* (f ( & ( SUP.sup sp1 ))) ≡ SUP.sup sp1) ∨ (* (f ( & ( SUP.sup sp1 ))) < SUP.sup sp1) z15 = SUP.x<sup sp1 (subst (λ k → odef chain k ) (sym &iso) (ZChain.f-next zc z12 )) z17 : ⊥ z17 with z15 ... | case1 eq = ¬b eq ... | case2 lt = ¬a lt -- ZChain contradicts ¬ Maximal -- -- ZChain forces fix point on any ≤-monotonic function (fixpoint) -- ¬ Maximal create cf which is a <-monotonic function by axiom of choice. This contradicts fix point of ZChain -- z04 : (nmx : ¬ Maximal A ) → (zc : ZChain A (cf nmx) (cf-is-≤-monotonic nmx) as0 (& A)) → ⊥ z04 nmx zc = <-irr0 {* (cf nmx c)} {* c} (subst (λ k → odef A k ) (sym &iso) (proj1 (is-cf nmx (SUP.as sp1 )))) (subst (λ k → odef A (& k)) (sym *iso) (SUP.as sp1) ) (case1 ( cong (*)( fixpoint (cf nmx) (cf-is-≤-monotonic nmx ) zc ))) -- x ≡ f x ̄ (proj1 (cf-is-<-monotonic nmx c (SUP.as sp1 ))) where -- x < f x sp1 : SUP A (ZChain.chain zc) sp1 = sp0 (cf nmx) (cf-is-≤-monotonic nmx) as0 zc c = & (SUP.sup sp1) uchain : ( f : Ordinal → Ordinal ) → (mf : ≤-monotonic-f A f ) {y : Ordinal} (ay : odef A y) → HOD uchain f mf {y} ay = record { od = record { def = λ x → FClosure A f y x } ; odmax = & A ; <odmax = λ {z} cz → subst (λ k → k o< & A) &iso ( c<→o< (subst (λ k → odef A k ) (sym &iso ) (A∋fc y f mf cz ))) } utotal : ( f : Ordinal → Ordinal ) → (mf : ≤-monotonic-f A f ) {y : Ordinal} (ay : odef A y) → IsTotalOrderSet (uchain f mf ay) utotal f mf {y} ay {a} {b} ca cb = subst₂ (λ j k → Tri (j < k) (j ≡ k) (k < j)) *iso *iso uz01 where uz01 : Tri (* (& a) < * (& b)) (* (& a) ≡ * (& b)) (* (& b) < * (& a) ) uz01 = fcn-cmp y f mf ca cb ysup : ( f : Ordinal → Ordinal ) → (mf : ≤-monotonic-f A f ) {y : Ordinal} (ay : odef A y) → SUP A (uchain f mf ay) ysup f mf {y} ay = supP (uchain f mf ay) (λ lt → A∋fc y f mf lt) (utotal f mf ay) SUP⊆ : { B C : HOD } → B ⊆' C → SUP A C → SUP A B SUP⊆ {B} {C} B⊆C sup = record { sup = SUP.sup sup ; as = SUP.as sup ; x<sup = λ lt → SUP.x<sup sup (B⊆C lt) } record xSUP (B : HOD) (x : Ordinal) : Set n where field ax : odef A x is-sup : IsSup A B ax -- -- create all ZChains under o< x -- ind : ( f : Ordinal → Ordinal ) → (mf : ≤-monotonic-f A f ) {y : Ordinal} (ay : odef A y) → (x : Ordinal) → ((z : Ordinal) → z o< x → ZChain A f mf ay z) → ZChain A f mf ay x ind f mf {y} ay x prev with Oprev-p x ... | yes op = zc4 where -- -- we have previous ordinal to use induction -- px = Oprev.oprev op zc : ZChain A f mf ay (Oprev.oprev op) zc = prev px (subst (λ k → px o< k) (Oprev.oprev=x op) <-osuc ) px<x : px o< x px<x = subst (λ k → px o< k) (Oprev.oprev=x op) <-osuc zc-b<x : (b : Ordinal ) → b o< x → b o< osuc px zc-b<x b lt = subst (λ k → b o< k ) (sym (Oprev.oprev=x op)) lt supf0 = ZChain.supf zc pchain : HOD pchain = UnionCF A f mf ay supf0 px -- ¬ supf0 px ≡ px → UnionCF supf0 px ≡ UnionCF supf1 x -- supf1 x ≡ supf0 px -- supf0 px ≡ px → ( UnionCF A f mf ay supf0 px ∪ FClosure px ) ≡ UnionCF supf1 x -- supf1 x ≡ sup of ( UnionCF A f mf ay supf0 px ∪ FClosure px (= UnionCF supf1 x))) ≥ supf0 px supf-mono : {a b : Ordinal } → a o≤ b → supf0 a o≤ supf0 b supf-mono = ZChain.supf-mono zc zc04 : {b : Ordinal} → b o≤ x → (b o≤ px ) ∨ (b ≡ x ) zc04 {b} b≤x with trio< b px ... | tri< a ¬b ¬c = case1 (o<→≤ a) ... | tri≈ ¬a b ¬c = case1 (o≤-refl0 b) ... | tri> ¬a ¬b px<b with osuc-≡< b≤x ... | case1 eq = case2 eq ... | case2 b<x = ⊥-elim ( ¬p<x<op ⟪ px<b , subst (λ k → b o< k ) (sym (Oprev.oprev=x op)) b<x ⟫ ) -- if previous chain satisfies maximality, we caan reuse it -- -- UninCF supf0 px previous chain u o< px, supf0 px is not included -- UninCF supf0 x supf0 px is included -- supf0 px ≡ px -- supf0 px ≡ supf0 x no-extension : ( (¬ xSUP (UnionCF A f mf ay supf0 px) x ) ∨ HasPrev A pchain x f) → ZChain A f mf ay x no-extension P with osuc-≡< (ZChain.x≤supfx zc ) ... | case1 sfpx=px = ? where pchainpx : HOD pchainpx = record { od = record { def = λ z → (odef A z ∧ UChain A f mf ay supf0 px z ) ∨ FClosure A f px z } ; odmax = & A ; <odmax = zc00 } where zc00 : {z : Ordinal } → (odef A z ∧ UChain A f mf ay supf0 px z ) ∨ FClosure A f px z → z o< & A zc00 {z} (case1 lt) = z07 lt zc00 {z} (case2 fc) = z09 ( A∋fc px f mf fc ) zc01 : {z : Ordinal } → (odef A z ∧ UChain A f mf ay supf0 px z ) ∨ FClosure A f px z → odef A z zc01 {z} (case1 lt) = proj1 lt zc01 {z} (case2 fc) = ( A∋fc px f mf fc ) zc02 : { a b : Ordinal } → odef A a ∧ UChain A f mf ay supf0 px a → FClosure A f px b → a <= b zc02 {a} {b} ca fb = zc05 fb where zc06 : & (SUP.sup (ZChain.sup zc o≤-refl)) ≡ px zc06 = trans (sym ( ZChain.supf-is-sup zc o≤-refl )) (sym sfpx=px) zc05 : {b : Ordinal } → FClosure A f px b → a <= b zc05 (fsuc b1 fb ) with proj1 ( mf b1 (A∋fc px f mf fb )) ... | case1 eq = subst (λ k → a <= k ) (subst₂ (λ j k → j ≡ k) &iso &iso (cong (&) eq)) (zc05 fb) ... | case2 lt = <-ftrans (zc05 fb) (case2 lt) zc05 (init b1 refl) with SUP.x<sup (ZChain.sup zc o≤-refl) (subst (λ k → odef A k ∧ UChain A f mf ay supf0 px k) (sym &iso) ca ) ... | case1 eq = case1 (subst₂ (λ j k → j ≡ k ) &iso zc06 (cong (&) eq)) ... | case2 lt = case2 (subst (λ k → (* a) < k ) (trans (sym *iso) (cong (*) zc06)) lt) ptotal : IsTotalOrderSet pchainpx ptotal (case1 a) (case1 b) = subst₂ (λ j k → Tri (j < k) (j ≡ k) (k < j)) *iso *iso (chain-total A f mf ay supf0 (proj2 a) (proj2 b)) ptotal {a0} {b0} (case1 a) (case2 b) with zc02 a b ... | case1 eq = tri≈ (<-irr (case1 (sym eq1))) eq1 (<-irr (case1 eq1)) where eq1 : a0 ≡ b0 eq1 = subst₂ (λ j k → j ≡ k ) *iso *iso (cong (*) eq ) ... | case2 lt = tri< lt1 (λ eq → <-irr (case1 (sym eq)) lt1) (<-irr (case2 lt1)) where lt1 : a0 < b0 lt1 = subst₂ (λ j k → j < k ) *iso *iso lt ptotal {b0} {a0} (case2 b) (case1 a) with zc02 a b ... | case1 eq = tri≈ (<-irr (case1 eq1)) (sym eq1) (<-irr (case1 (sym eq1))) where eq1 : a0 ≡ b0 eq1 = subst₂ (λ j k → j ≡ k ) *iso *iso (cong (*) eq ) ... | case2 lt = tri> (<-irr (case2 lt1)) (λ eq → <-irr (case1 eq) lt1) lt1 where lt1 : a0 < b0 lt1 = subst₂ (λ j k → j < k ) *iso *iso lt ptotal (case2 a) (case2 b) = subst₂ (λ j k → Tri (j < k) (j ≡ k) (k < j)) *iso *iso (fcn-cmp px f mf a b) sup1 : SUP A pchainpx sup1 = supP pchainpx zc01 ptotal sp1 : Ordinal sp1 = & (SUP.sup sup1 ) supf1 : Ordinal → Ordinal supf1 z with trio< z px ... | tri< a ¬b ¬c = supf0 z ... | tri≈ ¬a b ¬c = px --- supf px ≡ px ... | tri> ¬a ¬b c = sp1 pchainp : HOD pchainp = UnionCF A f mf ay supf1 x zc16 : {z : Ordinal } → z o< px → supf1 z ≡ supf0 z zc16 {z} z<px with trio< z px ... | tri< a ¬b ¬c = refl ... | tri≈ ¬a b ¬c = ⊥-elim ( ¬a z<px ) ... | tri> ¬a ¬b c = ⊥-elim ( ¬a z<px ) supf-mono1 : {z w : Ordinal } → z o≤ w → supf1 z o≤ supf1 w supf-mono1 {z} {w} z≤w with trio< w px ... | tri< a ¬b ¬c = subst₂ (λ j k → j o≤ k ) (sym (zc16 (ordtrans≤-< z≤w a))) refl ( supf-mono z≤w ) ... | tri≈ ¬a refl ¬c with osuc-≡< z≤w ... | case1 refl = o≤-refl0 zc17 where zc17 : supf1 px ≡ px zc17 with trio< px px ... | tri< a ¬b ¬c = ⊥-elim ( ¬b refl ) ... | tri≈ ¬a b ¬c = refl ... | tri> ¬a ¬b c = ⊥-elim ( ¬b refl ) ... | case2 lt = subst₂ (λ j k → j o≤ k ) (sym (zc16 lt)) (sym sfpx=px) ( supf-mono z≤w ) supf-mono1 {z} {w} z≤w | tri> ¬a ¬b c with trio< z px ... | tri< a ¬b ¬c = zc19 where zc19 : supf0 z o≤ sp1 zc19 = ? ... | tri≈ ¬a b ¬c = zc18 where zc18 : px o≤ sp1 zc18 = ? ... | tri> ¬a ¬b c = o≤-refl zc10 : {z : Ordinal} → OD.def (od pchain) z → OD.def (od pchainp) z zc10 {z} ⟪ az , ch-init fc ⟫ = ⟪ az , ch-init fc ⟫ zc10 {z} ⟪ az , ch-is-sup u1 u1<x u1-is-sup fc ⟫ = ⟪ az , ch-is-sup u1 (ordtrans u1<x (pxo<x op)) zc15 zc14 ⟫ where zc14 : FClosure A f (supf1 u1) z zc14 = subst (λ k → FClosure A f k z) (sym (zc16 u1<x)) fc zc15 : ChainP A f mf ay supf1 u1 zc15 = record { fcy<sup = λ {z} fcy → subst (λ k → (z ≡ k) ∨ ( z << k ) ) (sym (zc16 u1<x)) (ChainP.fcy<sup u1-is-sup fcy) ; order = λ {s} {z1} lt fc1 → subst (λ k → (z1 ≡ k) ∨ ( z1 << k ) ) (sym (zc16 u1<x)) ( ChainP.order u1-is-sup (subst₂ (λ j k → j o< k) (zc17 u1<x lt) (zc16 u1<x) lt) (subst (λ k → FClosure A f k z1) (zc17 u1<x lt) fc1) ) ; supu=u = trans (zc16 u1<x) (ChainP.supu=u u1-is-sup) } where zc17 : {s u : Ordinal } → u o< px → supf1 s o< supf1 u → supf1 s ≡ supf0 s zc17 u1<x lt = zc16 (ordtrans ( supf-inject0 supf-mono1 lt) u1<x) zc11 : {z : Ordinal} → z o< px → OD.def (od pchainp) z → OD.def (od pchain) z zc11 {z} z<px ⟪ az , ch-init fc ⟫ = ⟪ az , ch-init fc ⟫ zc11 {z} z<px ⟪ az , ch-is-sup u1 u1<x u1-is-sup fc ⟫ = ⟪ az , ch-is-sup u1 (ordtrans u1<x ?) ? ? ⟫ zc12 : {z : Ordinal} → OD.def (od pchainp) z → OD.def (od pchainpx) z zc12 {z} ⟪ az , ch-init fc ⟫ = case1 ⟪ az , ch-init fc ⟫ zc12 {z} ⟪ az , ch-is-sup u1 u1<x u1-is-sup fc ⟫ = ? zc13 : {z : Ordinal} → OD.def (od pchainpx) z → OD.def (od pchainp) z zc13 {z} (case1 ⟪ az , ch-init fc ⟫ ) = ⟪ az , ch-init fc ⟫ zc13 {z} (case1 ⟪ az , ch-is-sup u1 u1<x u1-is-sup fc ⟫ ) = ⟪ az , ch-is-sup u1 (ordtrans u1<x (pxo<x op)) ? ? ⟫ zc13 {z} (case2 fc) = ⟪ ? , ch-is-sup ? ? ? ? ⟫ record STMP {z : Ordinal} (z≤x : z o≤ x ) : Set (Level.suc n) where field tsup : SUP A (UnionCF A f mf ay supf1 z) tsup=sup : supf1 z ≡ & (SUP.sup tsup ) sup : {z : Ordinal} → (z≤x : z o≤ x ) → STMP z≤x sup {z} z≤x with trio< z px ... | tri< a ¬b ¬c = record { tsup = ? ; tsup=sup = ? } ... | tri≈ ¬a b ¬c = record { tsup = ? ; tsup=sup = ? } ... | tri> ¬a ¬b px<z = record { tsup = ? ; tsup=sup = ? } csupf1 : {b : Ordinal } → supf1 b o< x → odef (UnionCF A f mf ay supf1 x) (supf1 b) csupf1 {b} sb<z = ⟪ asb , ch-is-sup (supf1 b) sb<z record { fcy<sup = ? ; order = order ; supu=u = ? } (init ? ? ) ⟫ where b<x : b o< x b<x = ZChain.supf-inject zc ? asb : odef A (supf1 b) asb = ? -- ZChain.supf∈A zc ? -- (o<→≤ b<x) supb : SUP A (UnionCF A f mf ay supf1 (supf1 b)) supb = ? -- ZChain.sup zc (o<→≤ sb<z) supb-is-b : supf1 (supf1 b) ≡ & (SUP.sup supb) supb-is-b = ? -- ZChain.supf-is-sup zc ? -- (o<→≤ sb<z) order : {s z1 : Ordinal} → supf1 s o< supf1 (supf1 b) → FClosure A f (supf1 s) z1 → (z1 ≡ supf1 (supf1 b)) ∨ (z1 << supf1 (supf1 b)) order {s} {z1} ss<ssb fs with SUP.x<sup supb ? ... | case1 eq = ? ... | case2 lt = ? ... | case2 px<spfx = ? where -- record { supf = supf0 ; asupf = ZChain.asupf zc ; sup = λ lt → STMP.tsup (sup lt ) ; supf-mono = supf-mono -- ; supf-< = ? ; sup=u = sup=u ; supf-is-sup = λ lt → STMP.tsup=sup (sup lt) } where supf1 : Ordinal → Ordinal supf1 z with trio< z px ... | tri< a ¬b ¬c = supf0 z ... | tri≈ ¬a b ¬c = supf0 px ... | tri> ¬a ¬b c = supf0 px zc16 : {z : Ordinal } → z o< px → supf1 z ≡ supf0 z zc16 {z} z<px with trio< z px ... | tri< a ¬b ¬c = refl ... | tri≈ ¬a b ¬c = ⊥-elim ( ¬a z<px ) ... | tri> ¬a ¬b c = ⊥-elim ( ¬a z<px ) zc17 : {z : Ordinal } → supf0 z o≤ supf0 px zc17 = ? -- px o< z, px o< supf0 px supf-mono1 : {z w : Ordinal } → z o≤ w → supf1 z o≤ supf1 w supf-mono1 {z} {w} z≤w with trio< w px ... | tri< a ¬b ¬c = subst₂ (λ j k → j o≤ k ) (sym (zc16 (ordtrans≤-< z≤w a))) refl ( supf-mono z≤w ) ... | tri≈ ¬a refl ¬c with trio< z px ... | tri< a ¬b ¬c = zc17 ... | tri≈ ¬a refl ¬c = o≤-refl ... | tri> ¬a ¬b c = o≤-refl supf-mono1 {z} {w} z≤w | tri> ¬a ¬b c with trio< z px ... | tri< a ¬b ¬c = zc17 ... | tri≈ ¬a b ¬c = o≤-refl ... | tri> ¬a ¬b c = o≤-refl pchain1 : HOD pchain1 = UnionCF A f mf ay supf1 x zc10 : {z : Ordinal} → OD.def (od pchain) z → OD.def (od pchain1) z zc10 {z} ⟪ az , ch-init fc ⟫ = ⟪ az , ch-init fc ⟫ zc10 {z} ⟪ az , ch-is-sup u1 u1<x u1-is-sup fc ⟫ = ⟪ az , ch-is-sup u1 (ordtrans u1<x (pxo<x op)) ? ? ⟫ zc111 : {z : Ordinal} → z o< px → OD.def (od pchain1) z → OD.def (od pchain) z zc111 {z} z<px ⟪ az , ch-init fc ⟫ = ⟪ az , ch-init fc ⟫ zc111 {z} z<px ⟪ az , ch-is-sup u1 u1<x u1-is-sup fc ⟫ = ⟪ az , ch-is-sup u1 (ordtrans u1<x ?) ? ? ⟫ zc11 : (¬ xSUP (UnionCF A f mf ay supf0 px) x ) ∨ (HasPrev A pchain x f ) → {z : Ordinal} → OD.def (od pchain1) z → OD.def (od pchain) z ∨ ( (supf0 px ≡ px) ∧ FClosure A f px z ) zc11 P {z} ⟪ az , ch-init fc ⟫ = case1 ⟪ az , ch-init fc ⟫ zc11 P {z} ⟪ az , ch-is-sup u1 u1<x u1-is-sup fc ⟫ with trio< u1 px ... | tri< u1<px ¬b ¬c = case1 ⟪ az , ch-is-sup u1 u1<px ? fc ⟫ ... | tri≈ ¬a eq ¬c = case2 ⟪ subst (λ k → supf0 k ≡ k) eq s1u=u , subst (λ k → FClosure A f k z) zc12 ? ⟫ where s1u=u : supf0 u1 ≡ u1 s1u=u = ? -- ChainP.supu=u u1-is-sup zc12 : supf0 u1 ≡ px zc12 = trans s1u=u eq zc11 (case1 ¬sp=x) {z} ⟪ az , ch-is-sup u1 u1<x u1-is-sup fc ⟫ | tri> ¬a ¬b px<u = ⊥-elim (¬sp=x zcsup) where eq : u1 ≡ x eq with trio< u1 x ... | tri< a ¬b ¬c = ⊥-elim ( ¬p<x<op ⟪ px<u , subst (λ k → u1 o< k ) (sym (Oprev.oprev=x op )) a ⟫ ) ... | tri≈ ¬a b ¬c = b ... | tri> ¬a ¬b c = ⊥-elim ( o<> u1<x c ) s1u=x : supf0 u1 ≡ x s1u=x = trans ? eq zc13 : osuc px o< osuc u1 zc13 = o≤-refl0 ( trans (Oprev.oprev=x op) (sym eq ) ) x<sup : {w : Ordinal} → odef (UnionCF A f mf ay supf0 px) w → (w ≡ x) ∨ (w << x) x<sup {w} ⟪ az , ch-init {w} fc ⟫ = subst (λ k → (w ≡ k) ∨ (w << k)) s1u=x ? x<sup {w} ⟪ az , ch-is-sup u u<x is-sup fc ⟫ with osuc-≡< ( supf-mono (ordtrans (o<→≤ u<x) zc13 )) ... | case1 eq1 = ⊥-elim ( o<¬≡ zc14 (o<→≤ u<x) ) where zc14 : u ≡ osuc px zc14 = begin u ≡⟨ sym ( ChainP.supu=u is-sup) ⟩ supf0 u ≡⟨ eq1 ⟩ supf0 u1 ≡⟨ s1u=x ⟩ x ≡⟨ sym (Oprev.oprev=x op) ⟩ osuc px ∎ where open ≡-Reasoning ... | case2 lt = subst (λ k → (w ≡ k) ∨ (w << k)) s1u=x ? zc12 : supf0 x ≡ u1 zc12 = subst (λ k → supf0 k ≡ u1) eq ? zcsup : xSUP (UnionCF A f mf ay supf0 px) x zcsup = record { ax = subst (λ k → odef A k) (trans zc12 eq) (ZChain.asupf zc) ; is-sup = record { x<sup = x<sup } } zc11 (case2 hp) {z} ⟪ az , ch-is-sup u1 u1<x u1-is-sup fc ⟫ | tri> ¬a ¬b px<u = case1 ? where eq : u1 ≡ x eq with trio< u1 x ... | tri< a ¬b ¬c = ⊥-elim ( ¬p<x<op ⟪ px<u , subst (λ k → u1 o< k ) (sym (Oprev.oprev=x op )) a ⟫ ) ... | tri≈ ¬a b ¬c = b ... | tri> ¬a ¬b c = ⊥-elim ( o<> u1<x c ) zc20 : {z : Ordinal} → FClosure A f (supf0 u1) z → OD.def (od pchain) z zc20 {z} (init asu su=z ) = zc13 where zc14 : x ≡ z zc14 = begin x ≡⟨ sym eq ⟩ u1 ≡⟨ sym ? ⟩ supf0 u1 ≡⟨ su=z ⟩ z ∎ where open ≡-Reasoning zc13 : odef pchain z zc13 = subst (λ k → odef pchain k) (trans (sym (HasPrev.x=fy hp)) zc14) ( ZChain.f-next zc (HasPrev.ay hp) ) zc20 {.(f w)} (fsuc w fc) = ZChain.f-next zc (zc20 fc) record STMP {z : Ordinal} (z≤x : z o≤ x ) : Set (Level.suc n) where field tsup : SUP A (UnionCF A f mf ay supf0 z) tsup=sup : supf0 z ≡ & (SUP.sup tsup ) sup : {z : Ordinal} → (z≤x : z o≤ x ) → STMP z≤x sup {z} z≤x with trio< z px ... | tri< a ¬b ¬c = record { tsup = ZChain.sup zc (o<→≤ a) ; tsup=sup = ZChain.supf-is-sup zc (o<→≤ a) } ... | tri≈ ¬a b ¬c = record { tsup = ZChain.sup zc (o≤-refl0 b) ; tsup=sup = ZChain.supf-is-sup zc (o≤-refl0 b) } ... | tri> ¬a ¬b px<z = zc35 where zc30 : z ≡ x zc30 with osuc-≡< z≤x ... | case1 eq = eq ... | case2 z<x = ⊥-elim (¬p<x<op ⟪ px<z , subst (λ k → z o< k ) (sym (Oprev.oprev=x op)) z<x ⟫ ) zc32 = ZChain.sup zc o≤-refl zc34 : ¬ (supf0 px ≡ px) → {w : HOD} → UnionCF A f mf ay supf0 z ∋ w → (w ≡ SUP.sup zc32) ∨ (w < SUP.sup zc32) zc34 ne {w} lt with zc11 P ? ... | case1 lt = SUP.x<sup zc32 lt ... | case2 ⟪ spx=px , fc ⟫ = ⊥-elim ( ne spx=px ) zc33 : supf0 z ≡ & (SUP.sup zc32) zc33 = ? -- trans (sym (supfx (o≤-refl0 (sym zc30)))) ( ZChain.supf-is-sup zc o≤-refl ) zc36 : ¬ (supf0 px ≡ px) → STMP z≤x zc36 ne = record { tsup = record { sup = SUP.sup zc32 ; as = SUP.as zc32 ; x<sup = zc34 ne } ; tsup=sup = zc33 } zc35 : STMP z≤x zc35 with trio< (supf0 px) px ... | tri< a ¬b ¬c = zc36 ¬b ... | tri> ¬a ¬b c = zc36 ¬b ... | tri≈ ¬a b ¬c = record { tsup = zc37 ; tsup=sup = ? } where zc37 : SUP A (UnionCF A f mf ay supf0 z) zc37 = record { sup = ? ; as = ? ; x<sup = ? } sup=u : {b : Ordinal} (ab : odef A b) → b o≤ x → IsSup A (UnionCF A f mf ay supf0 b) ab ∧ (¬ HasPrev A (UnionCF A f mf ay supf0 b) b f ) → supf0 b ≡ b sup=u {b} ab b≤x is-sup with trio< b px ... | tri< a ¬b ¬c = ZChain.sup=u zc ab (o<→≤ a) ⟪ record { x<sup = λ lt → IsSup.x<sup (proj1 is-sup) lt } , proj2 is-sup ⟫ ... | tri≈ ¬a b ¬c = ZChain.sup=u zc ab (o≤-refl0 b) ⟪ record { x<sup = λ lt → IsSup.x<sup (proj1 is-sup) lt } , proj2 is-sup ⟫ ... | tri> ¬a ¬b px<b = zc31 P where zc30 : x ≡ b zc30 with osuc-≡< b≤x ... | case1 eq = sym (eq) ... | case2 b<x = ⊥-elim (¬p<x<op ⟪ px<b , subst (λ k → b o< k ) (sym (Oprev.oprev=x op)) b<x ⟫ ) zcsup : xSUP (UnionCF A f mf ay supf0 px) x zcsup with zc30 ... | refl = record { ax = ab ; is-sup = record { x<sup = λ {w} lt → IsSup.x<sup (proj1 is-sup) ?} } zc31 : ( (¬ xSUP (UnionCF A f mf ay supf0 px) x ) ∨ HasPrev A (UnionCF A f mf ay supf0 px) x f) → supf0 b ≡ b zc31 (case1 ¬sp=x) with zc30 ... | refl = ⊥-elim (¬sp=x zcsup ) zc31 (case2 hasPrev ) with zc30 ... | refl = ⊥-elim ( proj2 is-sup record { ax = HasPrev.ax hasPrev ; y = HasPrev.y hasPrev ; ay = ? ; x=fy = HasPrev.x=fy hasPrev } ) zc4 : ZChain A f mf ay x zc4 with ODC.∋-p O A (* x) ... | no noax = no-extension (case1 ( λ s → noax (subst (λ k → odef A k ) (sym &iso) (xSUP.ax s) ))) -- ¬ A ∋ p, just skip ... | yes ax with ODC.p∨¬p O ( HasPrev A (ZChain.chain zc ) x f ) -- we have to check adding x preserve is-max ZChain A y f mf x ... | case1 pr = no-extension (case2 pr) -- we have previous A ∋ z < x , f z ≡ x, so chain ∋ f z ≡ x because of f-next ... | case2 ¬fy<x with ODC.p∨¬p O (IsSup A (ZChain.chain zc ) ax ) ... | case1 is-sup = ? -- x is a sup of zc ... | case2 ¬x=sup = no-extension (case1 nsup) where -- px is not f y' nor sup of former ZChain from y -- no extention nsup : ¬ xSUP (UnionCF A f mf ay supf0 px) x nsup s = ¬x=sup z12 where z12 : IsSup A (UnionCF A f mf ay supf0 px) ax z12 = record { x<sup = λ {z} lt → subst (λ k → (z ≡ k) ∨ (z << k )) (sym &iso) ( IsSup.x<sup ( xSUP.is-sup s ) lt ) } ... | no lim = zc5 where pzc : (z : Ordinal) → z o< x → ZChain A f mf ay z pzc z z<x = prev z z<x ysp = & (SUP.sup (ysup f mf ay)) supf0 : Ordinal → Ordinal supf0 z with trio< z x ... | tri< a ¬b ¬c = ZChain.supf (pzc (osuc z) (ob<x lim a)) z ... | tri≈ ¬a b ¬c = ysp ... | tri> ¬a ¬b c = ysp pchain : HOD pchain = UnionCF A f mf ay supf0 x ptotal0 : IsTotalOrderSet pchain ptotal0 {a} {b} ca cb = subst₂ (λ j k → Tri (j < k) (j ≡ k) (k < j)) *iso *iso uz01 where uz01 : Tri (* (& a) < * (& b)) (* (& a) ≡ * (& b)) (* (& b) < * (& a) ) uz01 = chain-total A f mf ay supf0 ( (proj2 ca)) ( (proj2 cb)) usup : SUP A pchain usup = supP pchain (λ lt → proj1 lt) ptotal0 spu = & (SUP.sup usup) supf1 : Ordinal → Ordinal supf1 z with trio< z x ... | tri< a ¬b ¬c = ZChain.supf (pzc (osuc z) (ob<x lim a)) z ... | tri≈ ¬a b ¬c = spu ... | tri> ¬a ¬b c = spu pchain1 : HOD pchain1 = UnionCF A f mf ay supf1 x is-max-hp : (supf : Ordinal → Ordinal) (x : Ordinal) {a : Ordinal} {b : Ordinal} → odef (UnionCF A f mf ay supf x) a → b o< x → (ab : odef A b) → HasPrev A (UnionCF A f mf ay supf x) b f → * a < * b → odef (UnionCF A f mf ay supf x) b is-max-hp supf x {a} {b} ua b<x ab has-prev a<b with HasPrev.ay has-prev ... | ⟪ ab0 , ch-init fc ⟫ = ⟪ ab , ch-init ( subst (λ k → FClosure A f y k) (sym (HasPrev.x=fy has-prev)) (fsuc _ fc )) ⟫ ... | ⟪ ab0 , ch-is-sup u u≤x is-sup fc ⟫ = ⟪ ab , subst (λ k → UChain A f mf ay supf x k ) (sym (HasPrev.x=fy has-prev)) ( ch-is-sup u u≤x is-sup (fsuc _ fc)) ⟫ zc70 : HasPrev A pchain x f → ¬ xSUP pchain x zc70 pr xsup = ? no-extension : ¬ ( xSUP (UnionCF A f mf ay supf0 x) x ) → ZChain A f mf ay x no-extension ¬sp=x = ? where -- record { supf = supf1 ; sup=u = sup=u -- ; sup = sup ; supf-is-sup = sis ; supf-mono = {!!} ; asupf = ? } where supfu : {u : Ordinal } → ( a : u o< x ) → (z : Ordinal) → Ordinal supfu {u} a z = ZChain.supf (pzc (osuc u) (ob<x lim a)) z pchain0=1 : pchain ≡ pchain1 pchain0=1 = ==→o≡ record { eq→ = zc10 ; eq← = zc11 } where zc10 : {z : Ordinal} → OD.def (od pchain) z → OD.def (od pchain1) z zc10 {z} ⟪ az , ch-init fc ⟫ = ⟪ az , ch-init fc ⟫ zc10 {z} ⟪ az , ch-is-sup u u≤x is-sup fc ⟫ = zc12 fc where zc12 : {z : Ordinal} → FClosure A f (supf0 u) z → odef pchain1 z zc12 (fsuc x fc) with zc12 fc ... | ⟪ ua1 , ch-init fc₁ ⟫ = ⟪ proj2 ( mf _ ua1) , ch-init (fsuc _ fc₁) ⟫ ... | ⟪ ua1 , ch-is-sup u u≤x is-sup fc₁ ⟫ = ⟪ proj2 ( mf _ ua1) , ch-is-sup u u≤x is-sup (fsuc _ fc₁) ⟫ zc12 (init asu su=z ) = ⟪ subst (λ k → odef A k) su=z asu , ch-is-sup u u≤x ? (init ? ? ) ⟫ zc11 : {z : Ordinal} → OD.def (od pchain1) z → OD.def (od pchain) z zc11 {z} ⟪ az , ch-init fc ⟫ = ⟪ az , ch-init fc ⟫ zc11 {z} ⟪ az , ch-is-sup u u<x is-sup fc ⟫ = zc13 fc where zc13 : {z : Ordinal} → FClosure A f (supf1 u) z → odef pchain z zc13 (fsuc x fc) with zc13 fc ... | ⟪ ua1 , ch-init fc₁ ⟫ = ⟪ proj2 ( mf _ ua1) , ch-init (fsuc _ fc₁) ⟫ ... | ⟪ ua1 , ch-is-sup u u<x is-sup fc₁ ⟫ = ⟪ proj2 ( mf _ ua1) , ch-is-sup u u<x is-sup (fsuc _ fc₁) ⟫ zc13 (init asu su=z ) with trio< u x ... | tri< a ¬b ¬c = ⟪ ? , ch-is-sup u u<x ? (init ? ? ) ⟫ ... | tri≈ ¬a b ¬c = ? ... | tri> ¬a ¬b c = ? -- ⊥-elim ( o≤> u<x c ) sup : {z : Ordinal} → z o≤ x → SUP A (UnionCF A f mf ay supf1 z) sup {z} z≤x with trio< z x ... | tri< a ¬b ¬c = SUP⊆ ? (ZChain.sup (pzc (osuc z) {!!}) {!!} ) ... | tri≈ ¬a b ¬c = {!!} ... | tri> ¬a ¬b x<z = ⊥-elim (o<¬≡ refl (ordtrans<-≤ x<z z≤x )) sis : {z : Ordinal} (x≤z : z o≤ x) → supf1 z ≡ & (SUP.sup (sup {!!})) sis {z} z≤x with trio< z x ... | tri< a ¬b ¬c = {!!} where zc8 = ZChain.supf-is-sup (pzc z a) {!!} ... | tri≈ ¬a b ¬c = {!!} ... | tri> ¬a ¬b x<z = ⊥-elim (o<¬≡ refl (ordtrans<-≤ x<z z≤x )) sup=u : {b : Ordinal} (ab : odef A b) → b o≤ x → IsSup A (UnionCF A f mf ay supf1 b) ab ∧ (¬ HasPrev A (UnionCF A f mf ay supf1 b) b f ) → supf1 b ≡ b sup=u {z} ab z≤x is-sup with trio< z x ... | tri< a ¬b ¬c = ? -- ZChain.sup=u (pzc (osuc b) (ob<x lim a)) ab {!!} record { x<sup = {!!} } ... | tri≈ ¬a b ¬c = {!!} -- ZChain.sup=u (pzc (osuc ?) ?) ab {!!} record { x<sup = {!!} } ... | tri> ¬a ¬b x<z = ⊥-elim (o<¬≡ refl (ordtrans<-≤ x<z z≤x )) zc5 : ZChain A f mf ay x zc5 with ODC.∋-p O A (* x) ... | no noax = no-extension {!!} -- ¬ A ∋ p, just skip ... | yes ax with ODC.p∨¬p O ( HasPrev A pchain x f ) -- we have to check adding x preserve is-max ZChain A y f mf x ... | case1 pr = no-extension {!!} ... | case2 ¬fy<x with ODC.p∨¬p O (IsSup A pchain ax ) ... | case1 is-sup = ? -- record { supf = supf1 ; sup=u = {!!} -- ; sup = {!!} ; supf-is-sup = {!!} ; supf-mono = {!!}; asupf = {!!} } -- where -- x is a sup of (zc ?) ... | case2 ¬x=sup = no-extension {!!} -- x is not f y' nor sup of former ZChain from y -- no extention SZ : ( f : Ordinal → Ordinal ) → (mf : ≤-monotonic-f A f ) → {y : Ordinal} (ay : odef A y) → ZChain A f mf ay (& A) SZ f mf {y} ay = TransFinite {λ z → ZChain A f mf ay z } (λ x → ind f mf ay x ) (& A) zorn00 : Maximal A zorn00 with is-o∅ ( & HasMaximal ) -- we have no Level (suc n) LEM ... | no not = record { maximal = ODC.minimal O HasMaximal (λ eq → not (=od∅→≡o∅ eq)) ; as = zorn01 ; ¬maximal<x = zorn02 } where -- yes we have the maximal zorn03 : odef HasMaximal ( & ( ODC.minimal O HasMaximal (λ eq → not (=od∅→≡o∅ eq)) ) ) zorn03 = ODC.x∋minimal O HasMaximal (λ eq → not (=od∅→≡o∅ eq)) -- Axiom of choice zorn01 : A ∋ ODC.minimal O HasMaximal (λ eq → not (=od∅→≡o∅ eq)) zorn01 = proj1 zorn03 zorn02 : {x : HOD} → A ∋ x → ¬ (ODC.minimal O HasMaximal (λ eq → not (=od∅→≡o∅ eq)) < x) zorn02 {x} ax m<x = proj2 zorn03 (& x) ax (subst₂ (λ j k → j < k) (sym *iso) (sym *iso) m<x ) ... | yes ¬Maximal = ⊥-elim ( z04 nmx zorn04 ) where -- if we have no maximal, make ZChain, which contradict SUP condition nmx : ¬ Maximal A nmx mx = ∅< {HasMaximal} zc5 ( ≡o∅→=od∅ ¬Maximal ) where zc5 : odef A (& (Maximal.maximal mx)) ∧ (( y : Ordinal ) → odef A y → ¬ (* (& (Maximal.maximal mx)) < * y)) zc5 = ⟪ Maximal.as mx , (λ y ay mx<y → Maximal.¬maximal<x mx (subst (λ k → odef A k ) (sym &iso) ay) (subst (λ k → k < * y) *iso mx<y) ) ⟫ zorn04 : ZChain A (cf nmx) (cf-is-≤-monotonic nmx) as0 (& A) zorn04 = SZ (cf nmx) (cf-is-≤-monotonic nmx) (subst (λ k → odef A k ) &iso as ) -- usage (see filter.agda ) -- -- _⊆'_ : ( A B : HOD ) → Set n -- _⊆'_ A B = (x : Ordinal ) → odef A x → odef B x -- MaximumSubset : {L P : HOD} -- → o∅ o< & L → o∅ o< & P → P ⊆ L -- → IsPartialOrderSet P _⊆'_ -- → ( (B : HOD) → B ⊆ P → IsTotalOrderSet B _⊆'_ → SUP P B _⊆'_ ) -- → Maximal P (_⊆'_) -- MaximumSubset {L} {P} 0<L 0<P P⊆L PO SP = Zorn-lemma {P} {_⊆'_} 0<P PO SP