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PSet.equiv_of_isEmpty ** x : PSet y : PSet inst✝¹ : IsEmpty (Type x) inst✝ : IsEmpty (Type y) ⊒ (βˆ€ (i : Type x), βˆƒ j, Equiv (Func x i) (Func y j)) ∧ βˆ€ (j : Type y), βˆƒ i, Equiv (Func x i) (Func y j) ** simp ** Qed
PSet.func_mem ** x : PSet i : Type x ⊒ Func x i ∈ x ** cases x ** case mk α✝ : Type u_1 A✝ : α✝ β†’ PSet i : Type (mk α✝ A✝) ⊒ Func (mk α✝ A✝) i ∈ mk α✝ A✝ ** apply Mem.mk ** Qed
PSet.mem_wf_aux ** Ξ± : Type u A : Ξ± β†’ PSet Ξ² : Type u B : Ξ² β†’ PSet H : Equiv (mk Ξ± A) (mk Ξ² B) ⊒ βˆ€ (y : PSet), y ∈ mk Ξ² B β†’ Acc (fun x x_1 => x ∈ x_1) y ** rintro ⟨γ, C⟩ ⟨b, hc⟩ ** case mk.intro Ξ± : Type u A : Ξ± β†’ PSet Ξ² : Type u B : Ξ² β†’ PSet H : Equiv (mk Ξ± A) (mk Ξ² B) Ξ³ : Type u C : Ξ³ β†’ PSet b : Type (mk Ξ² B) hc : Equiv (mk Ξ³ C) (Func (mk Ξ² B) b) ⊒ Acc (fun x x_1 => x ∈ x_1) (mk Ξ³ C) ** cases' H.exists_right b with a ha ** case mk.intro.intro Ξ± : Type u A : Ξ± β†’ PSet Ξ² : Type u B : Ξ² β†’ PSet H : Equiv (mk Ξ± A) (mk Ξ² B) Ξ³ : Type u C : Ξ³ β†’ PSet b : Type (mk Ξ² B) hc : Equiv (mk Ξ³ C) (Func (mk Ξ² B) b) a : Type (mk Ξ± A) ha : Equiv (Func (mk Ξ± A) a) (Func (mk Ξ² B) b) ⊒ Acc (fun x x_1 => x ∈ x_1) (mk Ξ³ C) ** have H := ha.trans hc.symm ** case mk.intro.intro Ξ± : Type u A : Ξ± β†’ PSet Ξ² : Type u B : Ξ² β†’ PSet H✝ : Equiv (mk Ξ± A) (mk Ξ² B) Ξ³ : Type u C : Ξ³ β†’ PSet b : Type (mk Ξ² B) hc : Equiv (mk Ξ³ C) (Func (mk Ξ² B) b) a : Type (mk Ξ± A) ha : Equiv (Func (mk Ξ± A) a) (Func (mk Ξ² B) b) H : Equiv (Func (mk Ξ± A) a) (mk Ξ³ C) ⊒ Acc (fun x x_1 => x ∈ x_1) (mk Ξ³ C) ** rw [mk_func] at H ** case mk.intro.intro Ξ± : Type u A : Ξ± β†’ PSet Ξ² : Type u B : Ξ² β†’ PSet H✝ : Equiv (mk Ξ± A) (mk Ξ² B) Ξ³ : Type u C : Ξ³ β†’ PSet b : Type (mk Ξ² B) hc : Equiv (mk Ξ³ C) (Func (mk Ξ² B) b) a : Type (mk Ξ± A) ha : Equiv (Func (mk Ξ± A) a) (Func (mk Ξ² B) b) H : Equiv (A a) (mk Ξ³ C) ⊒ Acc (fun x x_1 => x ∈ x_1) (mk Ξ³ C) ** exact mem_wf_aux H ** Qed
PSet.toSet_empty ** ⊒ toSet βˆ… = βˆ… ** simp [toSet] ** Qed
PSet.not_nonempty_empty ** ⊒ Β¬PSet.Nonempty βˆ… ** simp [PSet.Nonempty] ** Qed
PSet.mem_sUnion ** Ξ± : Type u A : Ξ± β†’ PSet y : PSet x✝ : y ∈ ⋃₀ mk Ξ± A a : Type (mk Ξ± A) c : Type (Func (mk Ξ± A) a) e : Equiv y (Func (A a) c) this : Func (A a) c ∈ mk (Type (A a)) (Func (A a)) ⊒ Func (A a) c ∈ A (?m.24436 Ξ± A y x✝ a c e this) ** rwa [eta] at this ** Ξ± : Type u A : Ξ± β†’ PSet y : PSet x✝ : βˆƒ z, z ∈ mk Ξ± A ∧ y ∈ z Ξ² : Type u B : Ξ² β†’ PSet a : Type (mk Ξ± A) e : Equiv (mk Ξ² B) (A a) b : Type (mk Ξ² B) yb : Equiv y (Func (mk Ξ² B) b) ⊒ y ∈ ⋃₀ mk Ξ± A ** rw [← eta (A a)] at e ** Ξ± : Type u A : Ξ± β†’ PSet y : PSet x✝ : βˆƒ z, z ∈ mk Ξ± A ∧ y ∈ z Ξ² : Type u B : Ξ² β†’ PSet a : Type (mk Ξ± A) e : Equiv (mk Ξ² B) (mk (Type (A a)) (Func (A a))) b : Type (mk Ξ² B) yb : Equiv y (Func (mk Ξ² B) b) ⊒ y ∈ ⋃₀ mk Ξ± A ** exact let ⟨βt, _⟩ := e let ⟨c, bc⟩ := Ξ²t b ⟨⟨a, c⟩, yb.trans bc⟩ ** Qed
PSet.toSet_sUnion ** x : PSet ⊒ toSet (⋃₀ x) = ⋃₀ (toSet '' toSet x) ** ext ** case h x x✝ : PSet ⊒ x✝ ∈ toSet (⋃₀ x) ↔ x✝ ∈ ⋃₀ (toSet '' toSet x) ** simp ** Qed
ZFSet.toSet_subset_iff ** x y : ZFSet ⊒ toSet x βŠ† toSet y ↔ x βŠ† y ** simp [subset_def, Set.subset_def] ** Qed
ZFSet.ext_iff ** x y : ZFSet h : x = y ⊒ βˆ€ (z : ZFSet), z ∈ x ↔ z ∈ y ** simp [h] ** Qed
ZFSet.toSet_empty ** ⊒ toSet βˆ… = βˆ… ** simp [toSet] ** Qed
ZFSet.not_nonempty_empty ** ⊒ Β¬ZFSet.Nonempty βˆ… ** simp [ZFSet.Nonempty] ** Qed
ZFSet.nonempty_mk_iff ** x : PSet ⊒ ZFSet.Nonempty (mk x) ↔ PSet.Nonempty x ** refine' ⟨_, fun ⟨a, h⟩ => ⟨mk a, h⟩⟩ ** x : PSet ⊒ ZFSet.Nonempty (mk x) β†’ PSet.Nonempty x ** rintro ⟨a, h⟩ ** case intro x : PSet a : ZFSet h : a ∈ toSet (mk x) ⊒ PSet.Nonempty x ** induction a using Quotient.inductionOn ** case intro.h x a✝ : PSet h : Quotient.mk setoid a✝ ∈ toSet (mk x) ⊒ PSet.Nonempty x ** exact ⟨_, h⟩ ** Qed
ZFSet.eq_empty ** x : ZFSet ⊒ x = βˆ… ↔ βˆ€ (y : ZFSet), Β¬y ∈ x ** rw [ext_iff] ** x : ZFSet ⊒ (βˆ€ (z : ZFSet), z ∈ x ↔ z ∈ βˆ…) ↔ βˆ€ (y : ZFSet), Β¬y ∈ x ** simp ** Qed
ZFSet.eq_empty_or_nonempty ** u : ZFSet ⊒ u = βˆ… ∨ ZFSet.Nonempty u ** rw [eq_empty, ← not_exists] ** u : ZFSet ⊒ (Β¬βˆƒ x, x ∈ u) ∨ ZFSet.Nonempty u ** apply em' ** Qed
ZFSet.toSet_insert ** x y : ZFSet ⊒ toSet (insert x y) = insert x (toSet y) ** ext ** case h x y x✝ : ZFSet ⊒ x✝ ∈ toSet (insert x y) ↔ x✝ ∈ insert x (toSet y) ** simp ** Qed
ZFSet.toSet_singleton ** x : ZFSet ⊒ toSet {x} = {x} ** ext ** case h x x✝ : ZFSet ⊒ x✝ ∈ toSet {x} ↔ x✝ ∈ {x} ** simp ** Qed
ZFSet.mem_pair ** x y z : ZFSet ⊒ x ∈ {y, z} ↔ x = y ∨ x = z ** simp ** Qed
ZFSet.omega_succ ** n✝ : ZFSet x : PSet x✝ : Quotient.mk setoid x ∈ omega n : β„• h : PSet.Equiv x (Func PSet.omega { down := n }) ⊒ insert (mk x) (mk x) = insert (mk (ofNat n)) (mk (ofNat n)) ** rw [ZFSet.sound h] ** n✝ : ZFSet x : PSet x✝ : Quotient.mk setoid x ∈ omega n : β„• h : PSet.Equiv x (Func PSet.omega { down := n }) ⊒ insert (mk (Func PSet.omega { down := n })) (mk (Func PSet.omega { down := n })) = insert (mk (ofNat n)) (mk (ofNat n)) ** rfl ** Qed
ZFSet.mem_sep ** p : ZFSet β†’ Prop x y✝ : ZFSet x✝¹ y : PSet Ξ± : Type u A : Ξ± β†’ PSet x✝ : Quotient.mk setoid y ∈ ZFSet.sep p (Quotient.mk setoid (PSet.mk Ξ± A)) a : Type (PSet.mk Ξ± A) pa : (fun y => p (mk y)) (Func (PSet.mk Ξ± A) a) h : PSet.Equiv y (Func ↑(Resp.f { val := PSet.sep fun y => p (mk y), property := (_ : βˆ€ (x x_1 : PSet), PSet.Equiv x x_1 β†’ Arity.Equiv (PSet.sep (fun y => p (mk y)) x) (PSet.sep (fun y => p (mk y)) x_1)) } (PSet.mk Ξ± A)) { val := a, property := pa }) ⊒ p (Quotient.mk setoid y) ** rwa [@Quotient.sound PSet _ _ _ h] ** p : ZFSet β†’ Prop x y✝ : ZFSet x✝¹ y : PSet Ξ± : Type u A : Ξ± β†’ PSet x✝ : Quotient.mk setoid y ∈ Quotient.mk setoid (PSet.mk Ξ± A) ∧ p (Quotient.mk setoid y) a : Type (PSet.mk Ξ± A) h : PSet.Equiv y (Func (PSet.mk Ξ± A) a) pa : p (Quotient.mk setoid y) ⊒ (fun y => p (mk y)) (Func (PSet.mk Ξ± A) a) ** rw [mk_func] at h ** p : ZFSet β†’ Prop x y✝ : ZFSet x✝¹ y : PSet Ξ± : Type u A : Ξ± β†’ PSet x✝ : Quotient.mk setoid y ∈ Quotient.mk setoid (PSet.mk Ξ± A) ∧ p (Quotient.mk setoid y) a : Type (PSet.mk Ξ± A) h : PSet.Equiv y (A a) pa : p (Quotient.mk setoid y) ⊒ p (mk (Func (PSet.mk Ξ± A) a)) ** rwa [mk_func, ← ZFSet.sound h] ** Qed
ZFSet.toSet_sep ** a : ZFSet p : ZFSet β†’ Prop ⊒ toSet (ZFSet.sep p a) = {x | x ∈ toSet a ∧ p x} ** ext ** case h a : ZFSet p : ZFSet β†’ Prop x✝ : ZFSet ⊒ x✝ ∈ toSet (ZFSet.sep p a) ↔ x✝ ∈ {x | x ∈ toSet a ∧ p x} ** simp ** Qed
ZFSet.mem_powerset ** x y : ZFSet x✝¹ x✝ : PSet Ξ± : Type u A : Ξ± β†’ PSet Ξ² : Type u B : Ξ² β†’ PSet ⊒ PSet.mk Ξ² B ∈ PSet.powerset (PSet.mk Ξ± A) ↔ Quotient.mk setoid (PSet.mk Ξ² B) βŠ† Quotient.mk setoid (PSet.mk Ξ± A) ** simp [mem_powerset, subset_iff] ** Qed
ZFSet.sUnion_lem ** Ξ± Ξ² : Type u A : Ξ± β†’ PSet B : Ξ² β†’ PSet Ξ±Ξ² : βˆ€ (a : Ξ±), βˆƒ b, PSet.Equiv (A a) (B b) a : Type (PSet.mk Ξ± A) c : Type (Func (PSet.mk Ξ± A) a) ⊒ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) ** let ⟨b, hb⟩ := Ξ±Ξ² a ** Ξ± Ξ² : Type u A : Ξ± β†’ PSet B : Ξ² β†’ PSet Ξ±Ξ² : βˆ€ (a : Ξ±), βˆƒ b, PSet.Equiv (A a) (B b) a : Type (PSet.mk Ξ± A) c : Type (Func (PSet.mk Ξ± A) a) b : Ξ² hb : PSet.Equiv (A a) (B b) ⊒ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) ** induction' ea : A a with Ξ³ Ξ“ ** case mk Ξ± Ξ² : Type u A : Ξ± β†’ PSet B : Ξ² β†’ PSet Ξ±Ξ² : βˆ€ (a : Ξ±), βˆƒ b, PSet.Equiv (A a) (B b) a : Type (PSet.mk Ξ± A) c : Type (Func (PSet.mk Ξ± A) a) b : Ξ² hb : PSet.Equiv (A a) (B b) x✝ : PSet ea✝ : A a = x✝ Ξ³ : Type u Ξ“ : Ξ³ β†’ PSet A_ih✝ : βˆ€ (a_1 : Ξ³), A a = Ξ“ a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) ea : A a = PSet.mk Ξ³ Ξ“ ⊒ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) ** induction' eb : B b with Ξ΄ Ξ” ** case mk.mk Ξ± Ξ² : Type u A : Ξ± β†’ PSet B : Ξ² β†’ PSet Ξ±Ξ² : βˆ€ (a : Ξ±), βˆƒ b, PSet.Equiv (A a) (B b) a : Type (PSet.mk Ξ± A) c : Type (Func (PSet.mk Ξ± A) a) b : Ξ² hb : PSet.Equiv (A a) (B b) x✝¹ : PSet ea✝ : A a = x✝¹ Ξ³ : Type u Ξ“ : Ξ³ β†’ PSet A_ih✝¹ : βˆ€ (a_1 : Ξ³), A a = Ξ“ a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) ea : A a = PSet.mk Ξ³ Ξ“ x✝ : PSet eb✝ : B b = x✝ Ξ΄ : Type u Ξ” : Ξ΄ β†’ PSet A_ih✝ : βˆ€ (a_1 : Ξ΄), B b = Ξ” a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) eb : B b = PSet.mk Ξ΄ Ξ” ⊒ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) ** rw [ea, eb] at hb ** case mk.mk Ξ± Ξ² : Type u A : Ξ± β†’ PSet B : Ξ² β†’ PSet Ξ±Ξ² : βˆ€ (a : Ξ±), βˆƒ b, PSet.Equiv (A a) (B b) a : Type (PSet.mk Ξ± A) c : Type (Func (PSet.mk Ξ± A) a) b : Ξ² x✝¹ : PSet ea✝ : A a = x✝¹ Ξ³ : Type u Ξ“ : Ξ³ β†’ PSet A_ih✝¹ : βˆ€ (a_1 : Ξ³), A a = Ξ“ a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) ea : A a = PSet.mk Ξ³ Ξ“ x✝ : PSet eb✝ : B b = x✝ Ξ΄ : Type u Ξ” : Ξ΄ β†’ PSet hb : PSet.Equiv (PSet.mk Ξ³ Ξ“) (PSet.mk Ξ΄ Ξ”) A_ih✝ : βˆ€ (a_1 : Ξ΄), B b = Ξ” a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) eb : B b = PSet.mk Ξ΄ Ξ” ⊒ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) ** cases' hb with Ξ³Ξ΄ δγ ** case mk.mk.intro Ξ± Ξ² : Type u A : Ξ± β†’ PSet B : Ξ² β†’ PSet Ξ±Ξ² : βˆ€ (a : Ξ±), βˆƒ b, PSet.Equiv (A a) (B b) a : Type (PSet.mk Ξ± A) c : Type (Func (PSet.mk Ξ± A) a) b : Ξ² x✝¹ : PSet ea✝ : A a = x✝¹ Ξ³ : Type u Ξ“ : Ξ³ β†’ PSet A_ih✝¹ : βˆ€ (a_1 : Ξ³), A a = Ξ“ a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) ea : A a = PSet.mk Ξ³ Ξ“ x✝ : PSet eb✝ : B b = x✝ Ξ΄ : Type u Ξ” : Ξ΄ β†’ PSet A_ih✝ : βˆ€ (a_1 : Ξ΄), B b = Ξ” a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) eb : B b = PSet.mk Ξ΄ Ξ” Ξ³Ξ΄ : βˆ€ (a : Ξ³), βˆƒ b, PSet.Equiv (Ξ“ a) (Ξ” b) δγ : βˆ€ (b : Ξ΄), βˆƒ a, PSet.Equiv (Ξ“ a) (Ξ” b) ⊒ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c }) (Func (⋃₀ PSet.mk Ξ² B) b) ** let c : (A a).Type := c ** case mk.mk.intro Ξ± Ξ² : Type u A : Ξ± β†’ PSet B : Ξ² β†’ PSet Ξ±Ξ² : βˆ€ (a : Ξ±), βˆƒ b, PSet.Equiv (A a) (B b) a : Type (PSet.mk Ξ± A) c✝ : Type (Func (PSet.mk Ξ± A) a) b : Ξ² x✝¹ : PSet ea✝ : A a = x✝¹ Ξ³ : Type u Ξ“ : Ξ³ β†’ PSet A_ih✝¹ : βˆ€ (a_1 : Ξ³), A a = Ξ“ a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) ea : A a = PSet.mk Ξ³ Ξ“ x✝ : PSet eb✝ : B b = x✝ Ξ΄ : Type u Ξ” : Ξ΄ β†’ PSet A_ih✝ : βˆ€ (a_1 : Ξ΄), B b = Ξ” a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) eb : B b = PSet.mk Ξ΄ Ξ” Ξ³Ξ΄ : βˆ€ (a : Ξ³), βˆƒ b, PSet.Equiv (Ξ“ a) (Ξ” b) δγ : βˆ€ (b : Ξ΄), βˆƒ a, PSet.Equiv (Ξ“ a) (Ξ” b) c : Type (A a) := c✝ ⊒ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) ** let ⟨d, hd⟩ := Ξ³Ξ΄ (by rwa [ea] at c) ** case mk.mk.intro Ξ± Ξ² : Type u A : Ξ± β†’ PSet B : Ξ² β†’ PSet Ξ±Ξ² : βˆ€ (a : Ξ±), βˆƒ b, PSet.Equiv (A a) (B b) a : Type (PSet.mk Ξ± A) c✝ : Type (Func (PSet.mk Ξ± A) a) b : Ξ² x✝¹ : PSet ea✝ : A a = x✝¹ Ξ³ : Type u Ξ“ : Ξ³ β†’ PSet A_ih✝¹ : βˆ€ (a_1 : Ξ³), A a = Ξ“ a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) ea : A a = PSet.mk Ξ³ Ξ“ x✝ : PSet eb✝ : B b = x✝ Ξ΄ : Type u Ξ” : Ξ΄ β†’ PSet A_ih✝ : βˆ€ (a_1 : Ξ΄), B b = Ξ” a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) eb : B b = PSet.mk Ξ΄ Ξ” Ξ³Ξ΄ : βˆ€ (a : Ξ³), βˆƒ b, PSet.Equiv (Ξ“ a) (Ξ” b) δγ : βˆ€ (b : Ξ΄), βˆƒ a, PSet.Equiv (Ξ“ a) (Ξ” b) c : Type (A a) := c✝ d : Ξ΄ hd : PSet.Equiv (Ξ“ (Eq.mp (_ : Type (A a) = Type (PSet.mk Ξ³ Ξ“)) c)) (Ξ” d) ⊒ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) ** use ⟨b, Eq.ndrec d (Eq.symm eb)⟩ ** case h Ξ± Ξ² : Type u A : Ξ± β†’ PSet B : Ξ² β†’ PSet Ξ±Ξ² : βˆ€ (a : Ξ±), βˆƒ b, PSet.Equiv (A a) (B b) a : Type (PSet.mk Ξ± A) c✝ : Type (Func (PSet.mk Ξ± A) a) b : Ξ² x✝¹ : PSet ea✝ : A a = x✝¹ Ξ³ : Type u Ξ“ : Ξ³ β†’ PSet A_ih✝¹ : βˆ€ (a_1 : Ξ³), A a = Ξ“ a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) ea : A a = PSet.mk Ξ³ Ξ“ x✝ : PSet eb✝ : B b = x✝ Ξ΄ : Type u Ξ” : Ξ΄ β†’ PSet A_ih✝ : βˆ€ (a_1 : Ξ΄), B b = Ξ” a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) eb : B b = PSet.mk Ξ΄ Ξ” Ξ³Ξ΄ : βˆ€ (a : Ξ³), βˆƒ b, PSet.Equiv (Ξ“ a) (Ξ” b) δγ : βˆ€ (b : Ξ΄), βˆƒ a, PSet.Equiv (Ξ“ a) (Ξ” b) c : Type (A a) := c✝ d : Ξ΄ hd : PSet.Equiv (Ξ“ (Eq.mp (_ : Type (A a) = Type (PSet.mk Ξ³ Ξ“)) c)) (Ξ” d) ⊒ PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) { fst := b, snd := (_ : PSet.mk Ξ΄ Ξ” = Func (PSet.mk Ξ² B) b) β–Έ d }) ** change PSet.Equiv ((A a).Func c) ((B b).Func (Eq.ndrec d eb.symm)) ** case h Ξ± Ξ² : Type u A : Ξ± β†’ PSet B : Ξ² β†’ PSet Ξ±Ξ² : βˆ€ (a : Ξ±), βˆƒ b, PSet.Equiv (A a) (B b) a : Type (PSet.mk Ξ± A) c✝ : Type (Func (PSet.mk Ξ± A) a) b : Ξ² x✝¹ : PSet ea✝ : A a = x✝¹ Ξ³ : Type u Ξ“ : Ξ³ β†’ PSet A_ih✝¹ : βˆ€ (a_1 : Ξ³), A a = Ξ“ a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) ea : A a = PSet.mk Ξ³ Ξ“ x✝ : PSet eb✝ : B b = x✝ Ξ΄ : Type u Ξ” : Ξ΄ β†’ PSet A_ih✝ : βˆ€ (a_1 : Ξ΄), B b = Ξ” a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) eb : B b = PSet.mk Ξ΄ Ξ” Ξ³Ξ΄ : βˆ€ (a : Ξ³), βˆƒ b, PSet.Equiv (Ξ“ a) (Ξ” b) δγ : βˆ€ (b : Ξ΄), βˆƒ a, PSet.Equiv (Ξ“ a) (Ξ” b) c : Type (A a) := c✝ d : Ξ΄ hd : PSet.Equiv (Ξ“ (Eq.mp (_ : Type (A a) = Type (PSet.mk Ξ³ Ξ“)) c)) (Ξ” d) ⊒ PSet.Equiv (Func (A a) c) (Func (B b) ((_ : PSet.mk Ξ΄ Ξ” = B b) β–Έ d)) ** match A a, B b, ea, eb, c, d, hd with | _, _, rfl, rfl, _, _, hd => exact hd ** Ξ± Ξ² : Type u A : Ξ± β†’ PSet B : Ξ² β†’ PSet Ξ±Ξ² : βˆ€ (a : Ξ±), βˆƒ b, PSet.Equiv (A a) (B b) a : Type (PSet.mk Ξ± A) c✝ : Type (Func (PSet.mk Ξ± A) a) b : Ξ² x✝¹ : PSet ea✝ : A a = x✝¹ Ξ³ : Type u Ξ“ : Ξ³ β†’ PSet A_ih✝¹ : βˆ€ (a_1 : Ξ³), A a = Ξ“ a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) ea : A a = PSet.mk Ξ³ Ξ“ x✝ : PSet eb✝ : B b = x✝ Ξ΄ : Type u Ξ” : Ξ΄ β†’ PSet A_ih✝ : βˆ€ (a_1 : Ξ΄), B b = Ξ” a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) eb : B b = PSet.mk Ξ΄ Ξ” Ξ³Ξ΄ : βˆ€ (a : Ξ³), βˆƒ b, PSet.Equiv (Ξ“ a) (Ξ” b) δγ : βˆ€ (b : Ξ΄), βˆƒ a, PSet.Equiv (Ξ“ a) (Ξ” b) c : Type (A a) := c✝ ⊒ Ξ³ ** rwa [ea] at c ** Ξ± Ξ² : Type u A : Ξ± β†’ PSet B : Ξ² β†’ PSet Ξ±Ξ² : βˆ€ (a : Ξ±), βˆƒ b, PSet.Equiv (A a) (B b) a : Type (PSet.mk Ξ± A) c✝ : Type (Func (PSet.mk Ξ± A) a) b : Ξ² x✝³ : PSet ea✝ : A a = x✝³ Ξ³ : Type u Ξ“ : Ξ³ β†’ PSet A_ih✝¹ : βˆ€ (a_1 : Ξ³), A a = Ξ“ a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) ea : A a = PSet.mk Ξ³ Ξ“ x✝² : PSet eb✝ : B b = x✝² Ξ΄ : Type u Ξ” : Ξ΄ β†’ PSet A_ih✝ : βˆ€ (a_1 : Ξ΄), B b = Ξ” a_1 β†’ βˆƒ b, PSet.Equiv (Func (⋃₀ PSet.mk Ξ± A) { fst := a, snd := c✝ }) (Func (⋃₀ PSet.mk Ξ² B) b) eb : B b = PSet.mk Ξ΄ Ξ” Ξ³Ξ΄ : βˆ€ (a : Ξ³), βˆƒ b, PSet.Equiv (Ξ“ a) (Ξ” b) δγ : βˆ€ (b : Ξ΄), βˆƒ a, PSet.Equiv (Ξ“ a) (Ξ” b) c : Type (A a) := c✝ d : Ξ΄ hd✝ : PSet.Equiv (Ξ“ (Eq.mp (_ : Type (A a) = Type (PSet.mk Ξ³ Ξ“)) c)) (Ξ” d) x✝¹ : Type (PSet.mk Ξ³ Ξ“) x✝ : Ξ΄ hd : PSet.Equiv (Ξ“ (Eq.mp (_ : Type (PSet.mk Ξ³ Ξ“) = Type (PSet.mk Ξ³ Ξ“)) x✝¹)) (Ξ” x✝) ⊒ PSet.Equiv (Func (PSet.mk Ξ³ Ξ“) x✝¹) (Func (PSet.mk Ξ΄ Ξ”) ((_ : PSet.mk Ξ΄ Ξ” = PSet.mk Ξ΄ Ξ”) β–Έ x✝)) ** exact hd ** Qed
ZFSet.mem_sInter ** x y : ZFSet h : ZFSet.Nonempty x ⊒ y ∈ β‹‚β‚€ x ↔ βˆ€ (z : ZFSet), z ∈ x β†’ y ∈ z ** rw [sInter, dif_pos h] ** x y : ZFSet h : ZFSet.Nonempty x ⊒ y ∈ ZFSet.sep (fun y => βˆ€ (z : ZFSet), z ∈ x β†’ y ∈ z) (Set.Nonempty.some h) ↔ βˆ€ (z : ZFSet), z ∈ x β†’ y ∈ z ** simp only [mem_toSet, mem_sep, and_iff_right_iff_imp] ** x y : ZFSet h : ZFSet.Nonempty x ⊒ (βˆ€ (z : ZFSet), z ∈ x β†’ y ∈ z) β†’ y ∈ Set.Nonempty.some h ** exact fun H => H _ h.some_mem ** Qed
ZFSet.sUnion_empty ** ⊒ ⋃₀ βˆ… = βˆ… ** ext ** case a z✝ : ZFSet ⊒ z✝ ∈ ⋃₀ βˆ… ↔ z✝ ∈ βˆ… ** simp ** Qed
ZFSet.sInter_empty ** ⊒ Β¬ZFSet.Nonempty βˆ… ** simp ** Qed
ZFSet.mem_of_mem_sInter ** x y z : ZFSet hy : y ∈ β‹‚β‚€ x hz : z ∈ x ⊒ y ∈ z ** rcases eq_empty_or_nonempty x with (rfl | hx) ** case inl y z : ZFSet hy : y ∈ β‹‚β‚€ βˆ… hz : z ∈ βˆ… ⊒ y ∈ z ** exact (not_mem_empty z hz).elim ** case inr x y z : ZFSet hy : y ∈ β‹‚β‚€ x hz : z ∈ x hx : ZFSet.Nonempty x ⊒ y ∈ z ** exact (mem_sInter hx).1 hy z hz ** Qed
ZFSet.sUnion_singleton ** x y : ZFSet ⊒ y ∈ ⋃₀ {x} ↔ y ∈ x ** simp_rw [mem_sUnion, mem_singleton, exists_eq_left] ** Qed
ZFSet.sInter_singleton ** x y : ZFSet ⊒ y ∈ β‹‚β‚€ {x} ↔ y ∈ x ** simp_rw [mem_sInter (singleton_nonempty x), mem_singleton, forall_eq] ** Qed
ZFSet.toSet_sUnion ** x : ZFSet ⊒ toSet (⋃₀ x) = ⋃₀ (toSet '' toSet x) ** ext ** case h x x✝ : ZFSet ⊒ x✝ ∈ toSet (⋃₀ x) ↔ x✝ ∈ ⋃₀ (toSet '' toSet x) ** simp ** Qed
ZFSet.toSet_sInter ** x : ZFSet h : ZFSet.Nonempty x ⊒ toSet (β‹‚β‚€ x) = β‹‚β‚€ (toSet '' toSet x) ** ext ** case h x : ZFSet h : ZFSet.Nonempty x x✝ : ZFSet ⊒ x✝ ∈ toSet (β‹‚β‚€ x) ↔ x✝ ∈ β‹‚β‚€ (toSet '' toSet x) ** simp [mem_sInter h] ** Qed
ZFSet.singleton_injective ** x y : ZFSet H : {x} = {y} ⊒ x = y ** let this := congr_arg sUnion H ** x y : ZFSet H : {x} = {y} this : ⋃₀ {x} = ⋃₀ {y} := congr_arg sUnion H ⊒ x = y ** rwa [sUnion_singleton, sUnion_singleton] at this ** Qed
ZFSet.toSet_union ** x y : ZFSet ⊒ toSet (x βˆͺ y) = toSet x βˆͺ toSet y ** change (⋃₀ {x, y}).toSet = _ ** x y : ZFSet ⊒ toSet (⋃₀ {x, y}) = toSet x βˆͺ toSet y ** simp ** Qed
ZFSet.toSet_inter ** x y : ZFSet ⊒ toSet (x ∩ y) = toSet x ∩ toSet y ** change (ZFSet.sep (fun z => z ∈ y) x).toSet = _ ** x y : ZFSet ⊒ toSet (ZFSet.sep (fun z => z ∈ y) x) = toSet x ∩ toSet y ** ext ** case h x y x✝ : ZFSet ⊒ x✝ ∈ toSet (ZFSet.sep (fun z => z ∈ y) x) ↔ x✝ ∈ toSet x ∩ toSet y ** simp ** Qed
ZFSet.toSet_sdiff ** x y : ZFSet ⊒ toSet (x \ y) = toSet x \ toSet y ** change (ZFSet.sep (fun z => z βˆ‰ y) x).toSet = _ ** x y : ZFSet ⊒ toSet (ZFSet.sep (fun z => Β¬z ∈ y) x) = toSet x \ toSet y ** ext ** case h x y x✝ : ZFSet ⊒ x✝ ∈ toSet (ZFSet.sep (fun z => Β¬z ∈ y) x) ↔ x✝ ∈ toSet x \ toSet y ** simp ** Qed
ZFSet.mem_union ** x y z : ZFSet ⊒ z ∈ x βˆͺ y ↔ z ∈ x ∨ z ∈ y ** rw [← mem_toSet] ** x y z : ZFSet ⊒ z ∈ toSet (x βˆͺ y) ↔ z ∈ x ∨ z ∈ y ** simp ** Qed
ZFSet.toSet_image ** f : ZFSet β†’ ZFSet H : Definable 1 f x : ZFSet ⊒ toSet (image f x) = f '' toSet x ** ext ** case h f : ZFSet β†’ ZFSet H : Definable 1 f x x✝ : ZFSet ⊒ x✝ ∈ toSet (image f x) ↔ x✝ ∈ f '' toSet x ** simp ** Qed
ZFSet.mem_range ** Ξ± : Type u f : Ξ± β†’ ZFSet x : ZFSet y : PSet ⊒ Quotient.mk setoid y ∈ range f ↔ Quotient.mk setoid y ∈ Set.range f ** constructor ** case mp Ξ± : Type u f : Ξ± β†’ ZFSet x : ZFSet y : PSet ⊒ Quotient.mk setoid y ∈ range f β†’ Quotient.mk setoid y ∈ Set.range f ** rintro ⟨z, hz⟩ ** case mp.intro Ξ± : Type u f : Ξ± β†’ ZFSet x : ZFSet y : PSet z : Type (PSet.mk (ULift.{v, u} Ξ±) (Quotient.out ∘ f ∘ ULift.down)) hz : PSet.Equiv y (Func (PSet.mk (ULift.{v, u} Ξ±) (Quotient.out ∘ f ∘ ULift.down)) z) ⊒ Quotient.mk setoid y ∈ Set.range f ** exact ⟨z.down, Quotient.eq_mk_iff_out.2 hz.symm⟩ ** case mpr Ξ± : Type u f : Ξ± β†’ ZFSet x : ZFSet y : PSet ⊒ Quotient.mk setoid y ∈ Set.range f β†’ Quotient.mk setoid y ∈ range f ** rintro ⟨z, hz⟩ ** case mpr.intro Ξ± : Type u f : Ξ± β†’ ZFSet x : ZFSet y : PSet z : Ξ± hz : f z = Quotient.mk setoid y ⊒ Quotient.mk setoid y ∈ range f ** use ULift.up z ** case h Ξ± : Type u f : Ξ± β†’ ZFSet x : ZFSet y : PSet z : Ξ± hz : f z = Quotient.mk setoid y ⊒ PSet.Equiv y (Func (PSet.mk (ULift.{v, u} Ξ±) (Quotient.out ∘ f ∘ ULift.down)) { down := z }) ** simpa [hz] using PSet.Equiv.symm (Quotient.mk_out y) ** Qed
ZFSet.toSet_range ** Ξ± : Type u f : Ξ± β†’ ZFSet ⊒ toSet (range f) = Set.range f ** ext ** case h Ξ± : Type u f : Ξ± β†’ ZFSet x✝ : ZFSet ⊒ x✝ ∈ toSet (range f) ↔ x✝ ∈ Set.range f ** simp ** Qed
ZFSet.toSet_pair ** x y : ZFSet ⊒ toSet (pair x y) = {{x}, {x, y}} ** simp [pair] ** Qed
ZFSet.mem_pairSep ** p : ZFSet β†’ ZFSet β†’ Prop x y z : ZFSet ⊒ z ∈ pairSep p x y ↔ βˆƒ a, a ∈ x ∧ βˆƒ b, b ∈ y ∧ z = pair a b ∧ p a b ** refine' mem_sep.trans ⟨And.right, fun e => ⟨_, e⟩⟩ ** p : ZFSet β†’ ZFSet β†’ Prop x y z : ZFSet e : βˆƒ a, a ∈ x ∧ βˆƒ b, b ∈ y ∧ z = pair a b ∧ p a b ⊒ z ∈ powerset (powerset (x βˆͺ y)) ** rcases e with ⟨a, ax, b, bY, rfl, pab⟩ ** case intro.intro.intro.intro.intro p : ZFSet β†’ ZFSet β†’ Prop x y a : ZFSet ax : a ∈ x b : ZFSet bY : b ∈ y pab : p a b ⊒ pair a b ∈ powerset (powerset (x βˆͺ y)) ** simp only [mem_powerset, subset_def, mem_union, pair, mem_pair] ** case intro.intro.intro.intro.intro p : ZFSet β†’ ZFSet β†’ Prop x y a : ZFSet ax : a ∈ x b : ZFSet bY : b ∈ y pab : p a b ⊒ βˆ€ ⦃z : ZFSet⦄, z = {a} ∨ z = {a, b} β†’ βˆ€ ⦃z_1 : ZFSet⦄, z_1 ∈ z β†’ z_1 ∈ x ∨ z_1 ∈ y ** rintro u (rfl | rfl) v <;> simp only [mem_singleton, mem_pair] ** case intro.intro.intro.intro.intro.inl p : ZFSet β†’ ZFSet β†’ Prop x y a : ZFSet ax : a ∈ x b : ZFSet bY : b ∈ y pab : p a b v : ZFSet ⊒ v = a β†’ v ∈ x ∨ v ∈ y ** rintro rfl ** case intro.intro.intro.intro.intro.inl p : ZFSet β†’ ZFSet β†’ Prop x y b : ZFSet bY : b ∈ y v : ZFSet ax : v ∈ x pab : p v b ⊒ v ∈ x ∨ v ∈ y ** exact Or.inl ax ** case intro.intro.intro.intro.intro.inr p : ZFSet β†’ ZFSet β†’ Prop x y a : ZFSet ax : a ∈ x b : ZFSet bY : b ∈ y pab : p a b v : ZFSet ⊒ v = a ∨ v = b β†’ v ∈ x ∨ v ∈ y ** rintro (rfl | rfl) <;> [left; right] <;> assumption ** Qed
ZFSet.pair_injective ** x x' y y' : ZFSet H : pair x y = pair x' y' ⊒ x = x' ∧ y = y' ** have ae := ext_iff.1 H ** x x' y y' : ZFSet H : pair x y = pair x' y' ae : βˆ€ (z : ZFSet), z ∈ pair x y ↔ z ∈ pair x' y' ⊒ x = x' ∧ y = y' ** simp only [pair, mem_pair] at ae ** x y y' : ZFSet H : pair x y = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x} ∨ z = {x, y'} he : x = y β†’ y = y' ⊒ x = x ∧ y = y' ** obtain xyx | xyy' := (ae {x, y}).1 (by simp) ** x x' y y' : ZFSet H : pair x y = pair x' y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x'} ∨ z = {x', y'} ⊒ x = x' ** cases' (ae {x}).1 (by simp) with h h ** x x' y y' : ZFSet H : pair x y = pair x' y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x'} ∨ z = {x', y'} ⊒ {x} = {x} ∨ {x} = {x, y} ** simp ** case inl x x' y y' : ZFSet H : pair x y = pair x' y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x'} ∨ z = {x', y'} h : {x} = {x'} ⊒ x = x' ** exact singleton_injective h ** case inr x x' y y' : ZFSet H : pair x y = pair x' y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x'} ∨ z = {x', y'} h : {x} = {x', y'} ⊒ x = x' ** have m : x' ∈ ({x} : ZFSet) := by simp [h] ** case inr x x' y y' : ZFSet H : pair x y = pair x' y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x'} ∨ z = {x', y'} h : {x} = {x', y'} m : x' ∈ {x} ⊒ x = x' ** rw [mem_singleton.mp m] ** x x' y y' : ZFSet H : pair x y = pair x' y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x'} ∨ z = {x', y'} h : {x} = {x', y'} ⊒ x' ∈ {x} ** simp [h] ** x y y' : ZFSet H : pair x y = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x} ∨ z = {x, y'} ⊒ x = y β†’ y = y' ** rintro rfl ** x y' : ZFSet H : pair x x = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, x} ↔ z = {x} ∨ z = {x, y'} ⊒ x = y' ** cases' (ae {x, y'}).2 (by simp only [eq_self_iff_true, or_true_iff]) with xy'x xy'xx ** x y' : ZFSet H : pair x x = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, x} ↔ z = {x} ∨ z = {x, y'} ⊒ {x, y'} = {x} ∨ {x, y'} = {x, y'} ** simp only [eq_self_iff_true, or_true_iff] ** case inl x y' : ZFSet H : pair x x = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, x} ↔ z = {x} ∨ z = {x, y'} xy'x : {x, y'} = {x} ⊒ x = y' ** rw [eq_comm, ← mem_singleton, ← xy'x, mem_pair] ** case inl x y' : ZFSet H : pair x x = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, x} ↔ z = {x} ∨ z = {x, y'} xy'x : {x, y'} = {x} ⊒ y' = x ∨ y' = y' ** exact Or.inr rfl ** case inr x y' : ZFSet H : pair x x = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, x} ↔ z = {x} ∨ z = {x, y'} xy'xx : {x, y'} = {x, x} ⊒ x = y' ** simpa [eq_comm] using (ext_iff.1 xy'xx y').1 (by simp) ** x y' : ZFSet H : pair x x = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, x} ↔ z = {x} ∨ z = {x, y'} xy'xx : {x, y'} = {x, x} ⊒ y' ∈ {x, y'} ** simp ** x y y' : ZFSet H : pair x y = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x} ∨ z = {x, y'} he : x = y β†’ y = y' ⊒ {x, y} = {x} ∨ {x, y} = {x, y} ** simp ** case inl x y y' : ZFSet H : pair x y = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x} ∨ z = {x, y'} he : x = y β†’ y = y' xyx : {x, y} = {x} ⊒ x = x ∧ y = y' ** obtain rfl := mem_singleton.mp ((ext_iff.1 xyx y).1 <| by simp) ** case inl y y' : ZFSet H : pair y y = pair y y' ae : βˆ€ (z : ZFSet), z = {y} ∨ z = {y, y} ↔ z = {y} ∨ z = {y, y'} he : y = y β†’ y = y' xyx : {y, y} = {y} ⊒ y = y ∧ y = y' ** simp [he rfl] ** x y y' : ZFSet H : pair x y = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x} ∨ z = {x, y'} he : x = y β†’ y = y' xyx : {x, y} = {x} ⊒ y ∈ {x, y} ** simp ** case inr x y y' : ZFSet H : pair x y = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x} ∨ z = {x, y'} he : x = y β†’ y = y' xyy' : {x, y} = {x, y'} ⊒ x = x ∧ y = y' ** obtain rfl | yy' := mem_pair.mp ((ext_iff.1 xyy' y).1 <| by simp) ** x y y' : ZFSet H : pair x y = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x} ∨ z = {x, y'} he : x = y β†’ y = y' xyy' : {x, y} = {x, y'} ⊒ y ∈ {x, y} ** simp ** case inr.inl y y' : ZFSet H : pair y y = pair y y' ae : βˆ€ (z : ZFSet), z = {y} ∨ z = {y, y} ↔ z = {y} ∨ z = {y, y'} he : y = y β†’ y = y' xyy' : {y, y} = {y, y'} ⊒ y = y ∧ y = y' ** simp [he rfl] ** case inr.inr x y y' : ZFSet H : pair x y = pair x y' ae : βˆ€ (z : ZFSet), z = {x} ∨ z = {x, y} ↔ z = {x} ∨ z = {x, y'} he : x = y β†’ y = y' xyy' : {x, y} = {x, y'} yy' : y = y' ⊒ x = x ∧ y = y' ** simp [yy'] ** Qed
ZFSet.mem_prod ** x y z : ZFSet ⊒ z ∈ prod x y ↔ βˆƒ a, a ∈ x ∧ βˆƒ b, b ∈ y ∧ z = pair a b ** simp [prod] ** Qed
ZFSet.pair_mem_prod ** x y a b : ZFSet ⊒ pair a b ∈ prod x y ↔ a ∈ x ∧ b ∈ y ** simp ** Qed
ZFSet.mem_funs ** x y f : ZFSet ⊒ f ∈ funs x y ↔ IsFunc x y f ** simp [funs, IsFunc] ** Qed
ZFSet.map_unique ** f : ZFSet β†’ ZFSet H : Definable 1 f x z : ZFSet zx : z ∈ x y : ZFSet yx : (fun w => pair z w ∈ map f x) y ⊒ y = f z ** let ⟨w, _, we⟩ := mem_image.1 yx ** f : ZFSet β†’ ZFSet H : Definable 1 f x z : ZFSet zx : z ∈ x y : ZFSet yx : (fun w => pair z w ∈ map f x) y w : ZFSet left✝ : w ∈ x we : pair w (f w) = pair z y ⊒ y = f z ** let ⟨wz, fy⟩ := pair_injective we ** f : ZFSet β†’ ZFSet H : Definable 1 f x z : ZFSet zx : z ∈ x y : ZFSet yx : (fun w => pair z w ∈ map f x) y w : ZFSet left✝ : w ∈ x we : pair w (f w) = pair z y wz : w = z fy : f w = y ⊒ y = f z ** rw [← fy, wz] ** Qed
ZFSet.hereditarily_iff ** p : ZFSet β†’ Prop x y : ZFSet ⊒ Hereditarily p x ↔ p x ∧ βˆ€ (y : ZFSet), y ∈ x β†’ Hereditarily p y ** rw [← Hereditarily] ** Qed
ZFSet.Hereditarily.empty ** p : ZFSet β†’ Prop x y : ZFSet ⊒ Hereditarily p x β†’ p βˆ… ** apply @ZFSet.inductionOn _ x ** p : ZFSet β†’ Prop x y : ZFSet ⊒ βˆ€ (x : ZFSet), (βˆ€ (y : ZFSet), y ∈ x β†’ Hereditarily p y β†’ p βˆ…) β†’ Hereditarily p x β†’ p βˆ… ** intro y IH h ** p : ZFSet β†’ Prop x y✝ y : ZFSet IH : βˆ€ (y_1 : ZFSet), y_1 ∈ y β†’ Hereditarily p y_1 β†’ p βˆ… h : Hereditarily p y ⊒ p βˆ… ** rcases ZFSet.eq_empty_or_nonempty y with (rfl | ⟨a, ha⟩) ** case inl p : ZFSet β†’ Prop x y : ZFSet IH : βˆ€ (y : ZFSet), y ∈ βˆ… β†’ Hereditarily p y β†’ p βˆ… h : Hereditarily p βˆ… ⊒ p βˆ… ** exact h.self ** case inr.intro p : ZFSet β†’ Prop x y✝ y : ZFSet IH : βˆ€ (y_1 : ZFSet), y_1 ∈ y β†’ Hereditarily p y_1 β†’ p βˆ… h : Hereditarily p y a : ZFSet ha : a ∈ toSet y ⊒ p βˆ… ** exact IH a ha (h.mem ha) ** Qed
Class.mem_wf ** ⊒ βˆ€ (x : ZFSet), Acc (fun x x_1 => x ∈ x_1) ↑x ** refine' fun a => ZFSet.inductionOn a fun x IH => ⟨_, _⟩ ** a x : ZFSet IH : βˆ€ (y : ZFSet), y ∈ x β†’ Acc (fun x x_1 => x ∈ x_1) ↑y ⊒ βˆ€ (y : Class), y ∈ ↑x β†’ Acc (fun x x_1 => x ∈ x_1) y ** rintro A ⟨z, rfl, hz⟩ ** case intro.intro a x : ZFSet IH : βˆ€ (y : ZFSet), y ∈ x β†’ Acc (fun x x_1 => x ∈ x_1) ↑y z : ZFSet hz : ↑x z ⊒ Acc (fun x x_1 => x ∈ x_1) ↑z ** exact IH z hz ** H : βˆ€ (x : ZFSet), Acc (fun x x_1 => x ∈ x_1) ↑x ⊒ βˆ€ (a : Class), Acc (fun x x_1 => x ∈ x_1) a ** refine' fun A => ⟨A, _⟩ ** H : βˆ€ (x : ZFSet), Acc (fun x x_1 => x ∈ x_1) ↑x A : Class ⊒ βˆ€ (y : Class), y ∈ A β†’ Acc (fun x x_1 => x ∈ x_1) y ** rintro B ⟨x, rfl, _⟩ ** case intro.intro H : βˆ€ (x : ZFSet), Acc (fun x x_1 => x ∈ x_1) ↑x A : Class x : ZFSet right✝ : A x ⊒ Acc (fun x x_1 => x ∈ x_1) ↑x ** exact H x ** Qed
Class.congToClass_empty ** ⊒ congToClass βˆ… = βˆ… ** ext z ** case a z : ZFSet ⊒ congToClass βˆ… z ↔ βˆ… z ** simp only [congToClass, not_empty_hom, iff_false_iff] ** case a z : ZFSet ⊒ Β¬setOf (fun y => ↑y ∈ βˆ…) z ** exact Set.not_mem_empty z ** Qed
Class.classToCong_empty ** ⊒ classToCong βˆ… = βˆ… ** ext ** case h x✝ : Class ⊒ x✝ ∈ classToCong βˆ… ↔ x✝ ∈ βˆ… ** simp [classToCong] ** Qed
Class.ofSet.inj ** x y : ZFSet h : ↑x = ↑y z : ZFSet ⊒ z ∈ x ↔ z ∈ y ** change (x : Class.{u}) z ↔ (y : Class.{u}) z ** x y : ZFSet h : ↑x = ↑y z : ZFSet ⊒ ↑x z ↔ ↑y z ** rw [h] ** Qed
Class.toSet_of_ZFSet ** A : Class x : ZFSet x✝ : ToSet A ↑x y : ZFSet yx : ↑y = ↑x py : A y ⊒ A x ** rwa [ofSet.inj yx] at py ** Qed
Class.sUnion_apply ** x : Class y : ZFSet ⊒ (⋃₀ x) y ↔ βˆƒ z, x z ∧ y ∈ z ** constructor ** case mp x : Class y : ZFSet ⊒ (⋃₀ x) y β†’ βˆƒ z, x z ∧ y ∈ z ** rintro ⟨-, ⟨z, rfl, hxz⟩, hyz⟩ ** case mp.intro.intro.intro.intro x : Class y z : ZFSet hxz : x z hyz : y ∈ ↑z ⊒ βˆƒ z, x z ∧ y ∈ z ** exact ⟨z, hxz, hyz⟩ ** case mpr x : Class y : ZFSet ⊒ (βˆƒ z, x z ∧ y ∈ z) β†’ (⋃₀ x) y ** exact fun ⟨z, hxz, hyz⟩ => ⟨_, coe_mem.2 hxz, hyz⟩ ** Qed
Class.coe_sUnion ** x y : ZFSet ⊒ (βˆƒ z, ↑x z ∧ y ∈ z) ↔ βˆƒ z, z ∈ x ∧ y ∈ z ** rfl ** Qed
Class.mem_sUnion ** x y : Class ⊒ y ∈ ⋃₀ x ↔ βˆƒ z, z ∈ x ∧ y ∈ z ** constructor ** case mp x y : Class ⊒ y ∈ ⋃₀ x β†’ βˆƒ z, z ∈ x ∧ y ∈ z ** rintro ⟨w, rfl, z, hzx, hwz⟩ ** case mp.intro.intro.intro.intro x : Class w : ZFSet z : Set ZFSet hzx : z ∈ classToCong x hwz : w ∈ z ⊒ βˆƒ z, z ∈ x ∧ ↑w ∈ z ** exact ⟨z, hzx, coe_mem.2 hwz⟩ ** case mpr x y : Class ⊒ (βˆƒ z, z ∈ x ∧ y ∈ z) β†’ y ∈ ⋃₀ x ** rintro ⟨w, hwx, z, rfl, hwz⟩ ** case mpr.intro.intro.intro.intro x w : Class hwx : w ∈ x z : ZFSet hwz : w z ⊒ ↑z ∈ ⋃₀ x ** exact ⟨z, rfl, w, hwx, hwz⟩ ** Qed
Class.sInter_apply ** x : Class y : ZFSet ⊒ (β‹‚β‚€ x) y ↔ βˆ€ (z : ZFSet), x z β†’ y ∈ z ** refine' ⟨fun hxy z hxz => hxy _ ⟨z, rfl, hxz⟩, _⟩ ** x : Class y : ZFSet ⊒ (βˆ€ (z : ZFSet), x z β†’ y ∈ z) β†’ (β‹‚β‚€ x) y ** rintro H - ⟨z, rfl, hxz⟩ ** case intro.intro x : Class y : ZFSet H : βˆ€ (z : ZFSet), x z β†’ y ∈ z z : ZFSet hxz : x z ⊒ y ∈ ↑z ** exact H _ hxz ** Qed
Class.mem_of_mem_sInter ** x y z : Class hy : y ∈ β‹‚β‚€ x hz : z ∈ x ⊒ y ∈ z ** obtain ⟨w, rfl, hw⟩ := hy ** case intro.intro x z : Class hz : z ∈ x w : ZFSet hw : (β‹‚β‚€ x) w ⊒ ↑w ∈ z ** exact coe_mem.2 (hw z hz) ** Qed
Class.mem_sInter ** x y : Class h : Set.Nonempty x ⊒ y ∈ β‹‚β‚€ x ↔ βˆ€ (z : Class), z ∈ x β†’ y ∈ z ** refine' ⟨fun hy z => mem_of_mem_sInter hy, fun H => _⟩ ** x y : Class h : Set.Nonempty x H : βˆ€ (z : Class), z ∈ x β†’ y ∈ z ⊒ y ∈ β‹‚β‚€ x ** simp_rw [mem_def, sInter_apply] ** x y : Class h : Set.Nonempty x H : βˆ€ (z : Class), z ∈ x β†’ y ∈ z ⊒ βˆƒ x_1, ↑x_1 = y ∧ βˆ€ (z : ZFSet), x z β†’ x_1 ∈ z ** obtain ⟨z, hz⟩ := h ** case intro x y : Class H : βˆ€ (z : Class), z ∈ x β†’ y ∈ z z : ZFSet hz : z ∈ x ⊒ βˆƒ x_1, ↑x_1 = y ∧ βˆ€ (z : ZFSet), x z β†’ x_1 ∈ z ** obtain ⟨y, rfl, _⟩ := H z (coe_mem.2 hz) ** case intro.intro.intro x : Class z : ZFSet hz : z ∈ x y : ZFSet right✝ : ↑z y H : βˆ€ (z : Class), z ∈ x β†’ ↑y ∈ z ⊒ βˆƒ x_1, ↑x_1 = ↑y ∧ βˆ€ (z : ZFSet), x z β†’ x_1 ∈ z ** refine' ⟨y, rfl, fun w hxw => _⟩ ** case intro.intro.intro x : Class z : ZFSet hz : z ∈ x y : ZFSet right✝ : ↑z y H : βˆ€ (z : Class), z ∈ x β†’ ↑y ∈ z w : ZFSet hxw : x w ⊒ y ∈ w ** simpa only [coe_mem, coe_apply] using H w (coe_mem.2 hxw) ** Qed
Class.sUnion_empty ** ⊒ ⋃₀ βˆ… = βˆ… ** ext ** case a z✝ : ZFSet ⊒ (⋃₀ βˆ…) z✝ ↔ βˆ… z✝ ** simp ** Qed
Class.sInter_empty ** ⊒ β‹‚β‚€ βˆ… = univ ** rw [sInter, classToCong_empty, Set.sInter_empty, univ] ** Qed
Class.eq_univ_of_powerset_subset ** A : Class hA : powerset A βŠ† A ⊒ βˆ€ (x : ZFSet), A x ** by_contra' hnA ** A : Class hA : powerset A βŠ† A hnA : βˆƒ x, Β¬A x ⊒ False ** exact WellFounded.min_mem ZFSet.mem_wf _ hnA (hA fun x hx => Classical.not_not.1 fun hB => WellFounded.not_lt_min ZFSet.mem_wf _ hnA hB <| coe_apply.1 hx) ** Qed
Class.iota_val ** A : Class x : ZFSet H : βˆ€ (y : ZFSet), A y ↔ y = x y : ZFSet x✝ : iota A y x' : ZFSet h : setOf (fun x => βˆ€ (y : ZFSet), A y ↔ y = x) x' yx' : y ∈ ↑x' ⊒ ↑x y ** rwa [← (H x').1 <| (h x').2 rfl] ** Qed
ZFSet.map_fval ** f : ZFSet β†’ ZFSet H : PSet.Definable 1 f x y : ZFSet h : y ∈ x z : ZFSet ⊒ Class.ToSet (fun x_1 => ↑(map f x) (pair x_1 z)) ↑y ↔ z = f y ** rw [Class.toSet_of_ZFSet, Class.coe_apply, mem_map] ** f : ZFSet β†’ ZFSet H : PSet.Definable 1 f x y : ZFSet h : y ∈ x z : ZFSet ⊒ (βˆƒ z_1, z_1 ∈ x ∧ pair z_1 (f z_1) = pair y z) ↔ z = f y ** exact ⟨fun ⟨w, _, pr⟩ => by let ⟨wy, fw⟩ := ZFSet.pair_injective pr rw [← fw, wy], fun e => by subst e exact ⟨_, h, rfl⟩⟩ ** f : ZFSet β†’ ZFSet H : PSet.Definable 1 f x y : ZFSet h : y ∈ x z : ZFSet x✝ : βˆƒ z_1, z_1 ∈ x ∧ pair z_1 (f z_1) = pair y z w : ZFSet left✝ : w ∈ x pr : pair w (f w) = pair y z ⊒ z = f y ** let ⟨wy, fw⟩ := ZFSet.pair_injective pr ** f : ZFSet β†’ ZFSet H : PSet.Definable 1 f x y : ZFSet h : y ∈ x z : ZFSet x✝ : βˆƒ z_1, z_1 ∈ x ∧ pair z_1 (f z_1) = pair y z w : ZFSet left✝ : w ∈ x pr : pair w (f w) = pair y z wy : w = y fw : f w = z ⊒ z = f y ** rw [← fw, wy] ** f : ZFSet β†’ ZFSet H : PSet.Definable 1 f x y : ZFSet h : y ∈ x z : ZFSet e : z = f y ⊒ βˆƒ z_1, z_1 ∈ x ∧ pair z_1 (f z_1) = pair y z ** subst e ** f : ZFSet β†’ ZFSet H : PSet.Definable 1 f x y : ZFSet h : y ∈ x ⊒ βˆƒ z, z ∈ x ∧ pair z (f z) = pair y (f y) ** exact ⟨_, h, rfl⟩ ** Qed
ZFSet.choice_mem_aux ** x : ZFSet h : Β¬βˆ… ∈ x y : ZFSet yx : y ∈ x n : Β¬βˆƒ y_1, y_1 ∈ y ⊒ βˆ… ∈ x ** rwa [← (eq_empty y).2 fun z zx => n ⟨z, zx⟩] ** Qed
ZFSet.choice_mem ** x : ZFSet h : Β¬βˆ… ∈ x y : ZFSet yx : y ∈ x ⊒ ↑(choice x) β€² ↑y ∈ ↑y ** delta choice ** x : ZFSet h : Β¬βˆ… ∈ x y : ZFSet yx : y ∈ x ⊒ ↑(map (fun y => Classical.epsilon fun z => z ∈ y) x) β€² ↑y ∈ ↑y ** rw [@map_fval _ (Classical.allDefinable _) x y yx, Class.coe_mem, Class.coe_apply] ** x : ZFSet h : Β¬βˆ… ∈ x y : ZFSet yx : y ∈ x ⊒ (Classical.epsilon fun z => z ∈ y) ∈ y ** exact choice_mem_aux x h y yx ** Qed
SetTheory.PGame.turnBound_ne_zero_of_left_move ** S : Type u inst✝ : State S s t : S m : t ∈ l s ⊒ turnBound s β‰  0 ** intro h ** S : Type u inst✝ : State S s t : S m : t ∈ l s h : turnBound s = 0 ⊒ False ** have t := left_bound m ** S : Type u inst✝ : State S s t✝ : S m : t✝ ∈ l s h : turnBound s = 0 t : turnBound t✝ < turnBound s ⊒ False ** rw [h] at t ** S : Type u inst✝ : State S s t✝ : S m : t✝ ∈ l s h : turnBound s = 0 t : turnBound t✝ < 0 ⊒ False ** exact Nat.not_succ_le_zero _ t ** Qed
SetTheory.PGame.turnBound_ne_zero_of_right_move ** S : Type u inst✝ : State S s t : S m : t ∈ r s ⊒ turnBound s β‰  0 ** intro h ** S : Type u inst✝ : State S s t : S m : t ∈ r s h : turnBound s = 0 ⊒ False ** have t := right_bound m ** S : Type u inst✝ : State S s t✝ : S m : t✝ ∈ r s h : turnBound s = 0 t : turnBound t✝ < turnBound s ⊒ False ** rw [h] at t ** S : Type u inst✝ : State S s t✝ : S m : t✝ ∈ r s h : turnBound s = 0 t : turnBound t✝ < 0 ⊒ False ** exact Nat.not_succ_le_zero _ t ** Qed
SetTheory.PGame.wf_isOption ** x✝ x : PGame IHl : βˆ€ (i : LeftMoves x), Acc IsOption (moveLeft x i) IHr : βˆ€ (j : RightMoves x), Acc IsOption (moveRight x j) y : PGame h : IsOption y x ⊒ Acc IsOption y ** induction' h with _ i _ j ** case moveLeft x✝¹ x : PGame IHl✝ : βˆ€ (i : LeftMoves x), Acc IsOption (moveLeft x i) IHr✝ : βˆ€ (j : RightMoves x), Acc IsOption (moveRight x j) y x✝ : PGame i : LeftMoves x✝ IHl : βˆ€ (i : LeftMoves x✝), Acc IsOption (moveLeft x✝ i) IHr : βˆ€ (j : RightMoves x✝), Acc IsOption (moveRight x✝ j) ⊒ Acc IsOption (moveLeft x✝ i) ** exact IHl i ** case moveRight x✝¹ x : PGame IHl✝ : βˆ€ (i : LeftMoves x), Acc IsOption (moveLeft x i) IHr✝ : βˆ€ (j : RightMoves x), Acc IsOption (moveRight x j) y x✝ : PGame j : RightMoves x✝ IHl : βˆ€ (i : LeftMoves x✝), Acc IsOption (moveLeft x✝ i) IHr : βˆ€ (j : RightMoves x✝), Acc IsOption (moveRight x✝ j) ⊒ Acc IsOption (moveRight x✝ j) ** exact IHr j ** Qed
SetTheory.PGame.Subsequent.mk_right' ** xl xr : Type u_1 xL : xl β†’ PGame xR : xr β†’ PGame j : RightMoves (mk xl xr xL xR) ⊒ Subsequent (xR j) (mk xl xr xL xR) ** pgame_wf_tac ** Qed
SetTheory.PGame.Subsequent.moveRight_mk_left ** xl : Type u_1 i : xl xr : Type u_1 xR : xr β†’ PGame xL : xl β†’ PGame j : RightMoves (xL i) ⊒ Subsequent (PGame.moveRight (xL i) j) (mk xl xr xL xR) ** pgame_wf_tac ** Qed
SetTheory.PGame.Subsequent.moveRight_mk_right ** xr : Type u_1 i : xr xl : Type u_1 xL : xl β†’ PGame xR : xr β†’ PGame j : RightMoves (xR i) ⊒ Subsequent (PGame.moveRight (xR i) j) (mk xl xr xL xR) ** pgame_wf_tac ** Qed
SetTheory.PGame.Subsequent.moveLeft_mk_left ** xl : Type u_1 i : xl xr : Type u_1 xR : xr β†’ PGame xL : xl β†’ PGame j : LeftMoves (xL i) ⊒ Subsequent (PGame.moveLeft (xL i) j) (mk xl xr xL xR) ** pgame_wf_tac ** Qed
SetTheory.PGame.Subsequent.moveLeft_mk_right ** xr : Type u_1 i : xr xl : Type u_1 xL : xl β†’ PGame xR : xr β†’ PGame j : LeftMoves (xR i) ⊒ Subsequent (PGame.moveLeft (xR i) j) (mk xl xr xL xR) ** pgame_wf_tac ** Qed
SetTheory.PGame.le_iff_forall_lf ** x y : PGame ⊒ x ≀ y ↔ (βˆ€ (i : LeftMoves x), moveLeft x i ⧏ y) ∧ βˆ€ (j : RightMoves y), x ⧏ moveRight y j ** unfold LE.le le ** x y : PGame ⊒ { le := Sym2.GameAdd.fix wf_isOption fun x y le => (βˆ€ (i : LeftMoves x), Β¬le y (moveLeft x i) (_ : Sym2.GameAdd IsOption (Quotient.mk (Sym2.Rel.setoid PGame) (y, moveLeft x i)) (Quotient.mk (Sym2.Rel.setoid PGame) (x, y)))) ∧ βˆ€ (j : RightMoves y), Β¬le (moveRight y j) x (_ : Sym2.GameAdd IsOption (Quotient.mk (Sym2.Rel.setoid PGame) (moveRight y j, x)) (Quotient.mk (Sym2.Rel.setoid PGame) (x, y))) }.1 x y ↔ (βˆ€ (i : LeftMoves x), moveLeft x i ⧏ y) ∧ βˆ€ (j : RightMoves y), x ⧏ moveRight y j ** simp only ** x y : PGame ⊒ Sym2.GameAdd.fix wf_isOption (fun x y le => (βˆ€ (i : LeftMoves x), Β¬le y (moveLeft x i) (_ : Sym2.GameAdd IsOption (Quotient.mk (Sym2.Rel.setoid PGame) (y, moveLeft x i)) (Quotient.mk (Sym2.Rel.setoid PGame) (x, y)))) ∧ βˆ€ (j : RightMoves y), Β¬le (moveRight y j) x (_ : Sym2.GameAdd IsOption (Quotient.mk (Sym2.Rel.setoid PGame) (moveRight y j, x)) (Quotient.mk (Sym2.Rel.setoid PGame) (x, y)))) x y ↔ (βˆ€ (i : LeftMoves x), moveLeft x i ⧏ y) ∧ βˆ€ (j : RightMoves y), x ⧏ moveRight y j ** rw [Sym2.GameAdd.fix_eq] ** x y : PGame ⊒ ((βˆ€ (i : LeftMoves x), Β¬(fun a' b' x => Sym2.GameAdd.fix wf_isOption (fun x y le => (βˆ€ (i : LeftMoves x), Β¬le y (moveLeft x i) (_ : Sym2.GameAdd IsOption (Quotient.mk (Sym2.Rel.setoid PGame) (y, moveLeft x i)) (Quotient.mk (Sym2.Rel.setoid PGame) (x, y)))) ∧ βˆ€ (j : RightMoves y), Β¬le (moveRight y j) x (_ : Sym2.GameAdd IsOption (Quotient.mk (Sym2.Rel.setoid PGame) (moveRight y j, x)) (Quotient.mk (Sym2.Rel.setoid PGame) (x, y)))) a' b') y (moveLeft x i) (_ : Sym2.GameAdd IsOption (Quotient.mk (Sym2.Rel.setoid PGame) (y, moveLeft x i)) (Quotient.mk (Sym2.Rel.setoid PGame) (x, y)))) ∧ βˆ€ (j : RightMoves y), Β¬(fun a' b' x => Sym2.GameAdd.fix wf_isOption (fun x y le => (βˆ€ (i : LeftMoves x), Β¬le y (moveLeft x i) (_ : Sym2.GameAdd IsOption (Quotient.mk (Sym2.Rel.setoid PGame) (y, moveLeft x i)) (Quotient.mk (Sym2.Rel.setoid PGame) (x, y)))) ∧ βˆ€ (j : RightMoves y), Β¬le (moveRight y j) x (_ : Sym2.GameAdd IsOption (Quotient.mk (Sym2.Rel.setoid PGame) (moveRight y j, x)) (Quotient.mk (Sym2.Rel.setoid PGame) (x, y)))) a' b') (moveRight y j) x (_ : Sym2.GameAdd IsOption (Quotient.mk (Sym2.Rel.setoid PGame) (moveRight y j, x)) (Quotient.mk (Sym2.Rel.setoid PGame) (x, y)))) ↔ (βˆ€ (i : LeftMoves x), moveLeft x i ⧏ y) ∧ βˆ€ (j : RightMoves y), x ⧏ moveRight y j ** rfl ** Qed
SetTheory.PGame.lf_iff_exists_le ** x y : PGame ⊒ x ⧏ y ↔ (βˆƒ i, x ≀ moveLeft y i) ∨ βˆƒ j, moveRight x j ≀ y ** rw [LF, le_iff_forall_lf, not_and_or] ** x y : PGame ⊒ ((Β¬βˆ€ (i : LeftMoves y), moveLeft y i ⧏ x) ∨ Β¬βˆ€ (j : RightMoves x), y ⧏ moveRight x j) ↔ (βˆƒ i, x ≀ moveLeft y i) ∨ βˆƒ j, moveRight x j ≀ y ** simp ** Qed
SetTheory.PGame.le_or_gf ** x y : PGame ⊒ x ≀ y ∨ y ⧏ x ** rw [← PGame.not_le] ** x y : PGame ⊒ x ≀ y ∨ Β¬x ≀ y ** apply em ** Qed
SetTheory.PGame.lf_of_le_of_lf ** x y z : PGame h₁ : x ≀ y hβ‚‚ : y ⧏ z ⊒ x ⧏ z ** rw [← PGame.not_le] at hβ‚‚ ⊒ ** x y z : PGame h₁ : x ≀ y hβ‚‚ : Β¬z ≀ y ⊒ Β¬z ≀ x ** exact fun h₃ => hβ‚‚ (h₃.trans h₁) ** Qed
SetTheory.PGame.lf_of_lf_of_le ** x y z : PGame h₁ : x ⧏ y hβ‚‚ : y ≀ z ⊒ x ⧏ z ** rw [← PGame.not_le] at h₁ ⊒ ** x y z : PGame h₁ : Β¬y ≀ x hβ‚‚ : y ≀ z ⊒ Β¬z ≀ x ** exact fun h₃ => h₁ (hβ‚‚.trans h₃) ** Qed
SetTheory.PGame.le_def ** x y : PGame ⊒ x ≀ y ↔ (βˆ€ (i : LeftMoves x), (βˆƒ i', moveLeft x i ≀ moveLeft y i') ∨ βˆƒ j, moveRight (moveLeft x i) j ≀ y) ∧ βˆ€ (j : RightMoves y), (βˆƒ i, x ≀ moveLeft (moveRight y j) i) ∨ βˆƒ j', moveRight x j' ≀ moveRight y j ** rw [le_iff_forall_lf] ** x y : PGame ⊒ ((βˆ€ (i : LeftMoves x), moveLeft x i ⧏ y) ∧ βˆ€ (j : RightMoves y), x ⧏ moveRight y j) ↔ (βˆ€ (i : LeftMoves x), (βˆƒ i', moveLeft x i ≀ moveLeft y i') ∨ βˆƒ j, moveRight (moveLeft x i) j ≀ y) ∧ βˆ€ (j : RightMoves y), (βˆƒ i, x ≀ moveLeft (moveRight y j) i) ∨ βˆƒ j', moveRight x j' ≀ moveRight y j ** conv => lhs simp only [lf_iff_exists_le] ** Qed
SetTheory.PGame.lf_def ** x y : PGame ⊒ x ⧏ y ↔ (βˆƒ i, (βˆ€ (i' : LeftMoves x), moveLeft x i' ⧏ moveLeft y i) ∧ βˆ€ (j : RightMoves (moveLeft y i)), x ⧏ moveRight (moveLeft y i) j) ∨ βˆƒ j, (βˆ€ (i : LeftMoves (moveRight x j)), moveLeft (moveRight x j) i ⧏ y) ∧ βˆ€ (j' : RightMoves y), moveRight x j ⧏ moveRight y j' ** rw [lf_iff_exists_le] ** x y : PGame ⊒ ((βˆƒ i, x ≀ moveLeft y i) ∨ βˆƒ j, moveRight x j ≀ y) ↔ (βˆƒ i, (βˆ€ (i' : LeftMoves x), moveLeft x i' ⧏ moveLeft y i) ∧ βˆ€ (j : RightMoves (moveLeft y i)), x ⧏ moveRight (moveLeft y i) j) ∨ βˆƒ j, (βˆ€ (i : LeftMoves (moveRight x j)), moveLeft (moveRight x j) i ⧏ y) ∧ βˆ€ (j' : RightMoves y), moveRight x j ⧏ moveRight y j' ** conv => lhs simp only [le_iff_forall_lf] ** Qed
SetTheory.PGame.zero_le_lf ** x : PGame ⊒ 0 ≀ x ↔ βˆ€ (j : RightMoves x), 0 ⧏ moveRight x j ** rw [le_iff_forall_lf] ** x : PGame ⊒ ((βˆ€ (i : LeftMoves 0), moveLeft 0 i ⧏ x) ∧ βˆ€ (j : RightMoves x), 0 ⧏ moveRight x j) ↔ βˆ€ (j : RightMoves x), 0 ⧏ moveRight x j ** simp ** Qed
SetTheory.PGame.le_zero_lf ** x : PGame ⊒ x ≀ 0 ↔ βˆ€ (i : LeftMoves x), moveLeft x i ⧏ 0 ** rw [le_iff_forall_lf] ** x : PGame ⊒ ((βˆ€ (i : LeftMoves x), moveLeft x i ⧏ 0) ∧ βˆ€ (j : RightMoves 0), x ⧏ moveRight 0 j) ↔ βˆ€ (i : LeftMoves x), moveLeft x i ⧏ 0 ** simp ** Qed
SetTheory.PGame.zero_lf_le ** x : PGame ⊒ 0 ⧏ x ↔ βˆƒ i, 0 ≀ moveLeft x i ** rw [lf_iff_exists_le] ** x : PGame ⊒ ((βˆƒ i, 0 ≀ moveLeft x i) ∨ βˆƒ j, moveRight 0 j ≀ x) ↔ βˆƒ i, 0 ≀ moveLeft x i ** simp ** Qed
SetTheory.PGame.lf_zero_le ** x : PGame ⊒ x ⧏ 0 ↔ βˆƒ j, moveRight x j ≀ 0 ** rw [lf_iff_exists_le] ** x : PGame ⊒ ((βˆƒ i, x ≀ moveLeft 0 i) ∨ βˆƒ j, moveRight x j ≀ 0) ↔ βˆƒ j, moveRight x j ≀ 0 ** simp ** Qed
SetTheory.PGame.zero_le ** x : PGame ⊒ 0 ≀ x ↔ βˆ€ (j : RightMoves x), βˆƒ i, 0 ≀ moveLeft (moveRight x j) i ** rw [le_def] ** x : PGame ⊒ ((βˆ€ (i : LeftMoves 0), (βˆƒ i', moveLeft 0 i ≀ moveLeft x i') ∨ βˆƒ j, moveRight (moveLeft 0 i) j ≀ x) ∧ βˆ€ (j : RightMoves x), (βˆƒ i, 0 ≀ moveLeft (moveRight x j) i) ∨ βˆƒ j', moveRight 0 j' ≀ moveRight x j) ↔ βˆ€ (j : RightMoves x), βˆƒ i, 0 ≀ moveLeft (moveRight x j) i ** simp ** Qed
SetTheory.PGame.le_zero ** x : PGame ⊒ x ≀ 0 ↔ βˆ€ (i : LeftMoves x), βˆƒ j, moveRight (moveLeft x i) j ≀ 0 ** rw [le_def] ** x : PGame ⊒ ((βˆ€ (i : LeftMoves x), (βˆƒ i', moveLeft x i ≀ moveLeft 0 i') ∨ βˆƒ j, moveRight (moveLeft x i) j ≀ 0) ∧ βˆ€ (j : RightMoves 0), (βˆƒ i, x ≀ moveLeft (moveRight 0 j) i) ∨ βˆƒ j', moveRight x j' ≀ moveRight 0 j) ↔ βˆ€ (i : LeftMoves x), βˆƒ j, moveRight (moveLeft x i) j ≀ 0 ** simp ** Qed
SetTheory.PGame.zero_lf ** x : PGame ⊒ 0 ⧏ x ↔ βˆƒ i, βˆ€ (j : RightMoves (moveLeft x i)), 0 ⧏ moveRight (moveLeft x i) j ** rw [lf_def] ** x : PGame ⊒ ((βˆƒ i, (βˆ€ (i' : LeftMoves 0), moveLeft 0 i' ⧏ moveLeft x i) ∧ βˆ€ (j : RightMoves (moveLeft x i)), 0 ⧏ moveRight (moveLeft x i) j) ∨ βˆƒ j, (βˆ€ (i : LeftMoves (moveRight 0 j)), moveLeft (moveRight 0 j) i ⧏ x) ∧ βˆ€ (j' : RightMoves x), moveRight 0 j ⧏ moveRight x j') ↔ βˆƒ i, βˆ€ (j : RightMoves (moveLeft x i)), 0 ⧏ moveRight (moveLeft x i) j ** simp ** Qed
SetTheory.PGame.lf_zero ** x : PGame ⊒ x ⧏ 0 ↔ βˆƒ j, βˆ€ (i : LeftMoves (moveRight x j)), moveLeft (moveRight x j) i ⧏ 0 ** rw [lf_def] ** x : PGame ⊒ ((βˆƒ i, (βˆ€ (i' : LeftMoves x), moveLeft x i' ⧏ moveLeft 0 i) ∧ βˆ€ (j : RightMoves (moveLeft 0 i)), x ⧏ moveRight (moveLeft 0 i) j) ∨ βˆƒ j, (βˆ€ (i : LeftMoves (moveRight x j)), moveLeft (moveRight x j) i ⧏ 0) ∧ βˆ€ (j' : RightMoves 0), moveRight x j ⧏ moveRight 0 j') ↔ βˆƒ j, βˆ€ (i : LeftMoves (moveRight x j)), moveLeft (moveRight x j) i ⧏ 0 ** simp ** Qed
SetTheory.PGame.equiv_of_eq ** x y : PGame h : x = y ⊒ x β‰ˆ y ** subst h ** x : PGame ⊒ x β‰ˆ x ** rfl ** Qed
SetTheory.PGame.lf_or_equiv_or_gf ** x y : PGame ⊒ x ⧏ y ∨ x β‰ˆ y ∨ y ⧏ x ** by_cases h : x ⧏ y ** case pos x y : PGame h : x ⧏ y ⊒ x ⧏ y ∨ x β‰ˆ y ∨ y ⧏ x ** exact Or.inl h ** case neg x y : PGame h : Β¬x ⧏ y ⊒ x ⧏ y ∨ x β‰ˆ y ∨ y ⧏ x ** right ** case neg.h x y : PGame h : Β¬x ⧏ y ⊒ x β‰ˆ y ∨ y ⧏ x ** cases' lt_or_equiv_of_le (PGame.not_lf.1 h) with h' h' ** case neg.h.inl x y : PGame h : Β¬x ⧏ y h' : y < x ⊒ x β‰ˆ y ∨ y ⧏ x ** exact Or.inr h'.lf ** case neg.h.inr x y : PGame h : Β¬x ⧏ y h' : y β‰ˆ x ⊒ x β‰ˆ y ∨ y ⧏ x ** exact Or.inl (Equiv.symm h') ** Qed
SetTheory.PGame.equiv_of_mk_equiv ** x y : PGame L : LeftMoves x ≃ LeftMoves y R : RightMoves x ≃ RightMoves y hl : βˆ€ (i : LeftMoves x), moveLeft x i β‰ˆ moveLeft y (↑L i) hr : βˆ€ (j : RightMoves x), moveRight x j β‰ˆ moveRight y (↑R j) ⊒ x β‰ˆ y ** constructor <;> rw [le_def] ** case left x y : PGame L : LeftMoves x ≃ LeftMoves y R : RightMoves x ≃ RightMoves y hl : βˆ€ (i : LeftMoves x), moveLeft x i β‰ˆ moveLeft y (↑L i) hr : βˆ€ (j : RightMoves x), moveRight x j β‰ˆ moveRight y (↑R j) ⊒ (βˆ€ (i : LeftMoves x), (βˆƒ i', moveLeft x i ≀ moveLeft y i') ∨ βˆƒ j, moveRight (moveLeft x i) j ≀ y) ∧ βˆ€ (j : RightMoves y), (βˆƒ i, x ≀ moveLeft (moveRight y j) i) ∨ βˆƒ j', moveRight x j' ≀ moveRight y j ** exact ⟨fun i => Or.inl ⟨_, (hl i).1⟩, fun j => Or.inr ⟨_, by simpa using (hr (R.symm j)).1⟩⟩ ** x y : PGame L : LeftMoves x ≃ LeftMoves y R : RightMoves x ≃ RightMoves y hl : βˆ€ (i : LeftMoves x), moveLeft x i β‰ˆ moveLeft y (↑L i) hr : βˆ€ (j : RightMoves x), moveRight x j β‰ˆ moveRight y (↑R j) j : RightMoves y ⊒ moveRight x (?m.65566 j) ≀ moveRight y j ** simpa using (hr (R.symm j)).1 ** case right x y : PGame L : LeftMoves x ≃ LeftMoves y R : RightMoves x ≃ RightMoves y hl : βˆ€ (i : LeftMoves x), moveLeft x i β‰ˆ moveLeft y (↑L i) hr : βˆ€ (j : RightMoves x), moveRight x j β‰ˆ moveRight y (↑R j) ⊒ (βˆ€ (i : LeftMoves y), (βˆƒ i', moveLeft y i ≀ moveLeft x i') ∨ βˆƒ j, moveRight (moveLeft y i) j ≀ x) ∧ βˆ€ (j : RightMoves x), (βˆƒ i, y ≀ moveLeft (moveRight x j) i) ∨ βˆƒ j', moveRight y j' ≀ moveRight x j ** exact ⟨fun i => Or.inl ⟨_, by simpa using (hl (L.symm i)).2⟩, fun j => Or.inr ⟨_, (hr j).2⟩⟩ ** x y : PGame L : LeftMoves x ≃ LeftMoves y R : RightMoves x ≃ RightMoves y hl : βˆ€ (i : LeftMoves x), moveLeft x i β‰ˆ moveLeft y (↑L i) hr : βˆ€ (j : RightMoves x), moveRight x j β‰ˆ moveRight y (↑R j) i : LeftMoves y ⊒ moveLeft y i ≀ moveLeft x (?m.66250 i) ** simpa using (hl (L.symm i)).2 ** Qed
SetTheory.PGame.lf_iff_lt_or_fuzzy ** x y : PGame ⊒ x ⧏ y ↔ x < y ∨ x β€– y ** simp only [lt_iff_le_and_lf, Fuzzy, ← PGame.not_le] ** x y : PGame ⊒ Β¬y ≀ x ↔ x ≀ y ∧ Β¬y ≀ x ∨ Β¬y ≀ x ∧ Β¬x ≀ y ** tauto ** Qed
SetTheory.PGame.fuzzy_congr ** x₁ y₁ xβ‚‚ yβ‚‚ : PGame hx : x₁ β‰ˆ xβ‚‚ hy : y₁ β‰ˆ yβ‚‚ ⊒ x₁ ⧏ y₁ ∧ y₁ ⧏ x₁ ↔ xβ‚‚ ⧏ yβ‚‚ ∧ yβ‚‚ ⧏ xβ‚‚ ** rw [lf_congr hx hy, lf_congr hy hx] ** Qed
SetTheory.PGame.lt_or_equiv_or_gt_or_fuzzy ** x y : PGame ⊒ x < y ∨ x β‰ˆ y ∨ y < x ∨ x β€– y ** cases' le_or_gf x y with h₁ h₁ <;> cases' le_or_gf y x with hβ‚‚ hβ‚‚ ** case inl.inl x y : PGame h₁ : x ≀ y hβ‚‚ : y ≀ x ⊒ x < y ∨ x β‰ˆ y ∨ y < x ∨ x β€– y ** right ** case inl.inl.h x y : PGame h₁ : x ≀ y hβ‚‚ : y ≀ x ⊒ x β‰ˆ y ∨ y < x ∨ x β€– y ** left ** case inl.inl.h.h x y : PGame h₁ : x ≀ y hβ‚‚ : y ≀ x ⊒ x β‰ˆ y ** exact ⟨h₁, hβ‚‚βŸ© ** case inl.inr x y : PGame h₁ : x ≀ y hβ‚‚ : x ⧏ y ⊒ x < y ∨ x β‰ˆ y ∨ y < x ∨ x β€– y ** left ** case inl.inr.h x y : PGame h₁ : x ≀ y hβ‚‚ : x ⧏ y ⊒ x < y ** exact ⟨h₁, hβ‚‚βŸ© ** case inr.inl x y : PGame h₁ : y ⧏ x hβ‚‚ : y ≀ x ⊒ x < y ∨ x β‰ˆ y ∨ y < x ∨ x β€– y ** right ** case inr.inl.h x y : PGame h₁ : y ⧏ x hβ‚‚ : y ≀ x ⊒ x β‰ˆ y ∨ y < x ∨ x β€– y ** right ** case inr.inl.h.h x y : PGame h₁ : y ⧏ x hβ‚‚ : y ≀ x ⊒ y < x ∨ x β€– y ** left ** case inr.inl.h.h.h x y : PGame h₁ : y ⧏ x hβ‚‚ : y ≀ x ⊒ y < x ** exact ⟨hβ‚‚, hβ‚βŸ© ** case inr.inr x y : PGame h₁ : y ⧏ x hβ‚‚ : x ⧏ y ⊒ x < y ∨ x β‰ˆ y ∨ y < x ∨ x β€– y ** right ** case inr.inr.h x y : PGame h₁ : y ⧏ x hβ‚‚ : x ⧏ y ⊒ x β‰ˆ y ∨ y < x ∨ x β€– y ** right ** case inr.inr.h.h x y : PGame h₁ : y ⧏ x hβ‚‚ : x ⧏ y ⊒ y < x ∨ x β€– y ** right ** case inr.inr.h.h.h x y : PGame h₁ : y ⧏ x hβ‚‚ : x ⧏ y ⊒ x β€– y ** exact ⟨hβ‚‚, hβ‚βŸ© ** Qed
SetTheory.PGame.lt_or_equiv_or_gf ** x y : PGame ⊒ x < y ∨ x β‰ˆ y ∨ y ⧏ x ** rw [lf_iff_lt_or_fuzzy, Fuzzy.swap_iff] ** x y : PGame ⊒ x < y ∨ x β‰ˆ y ∨ y < x ∨ x β€– y ** exact lt_or_equiv_or_gt_or_fuzzy x y ** Qed
SetTheory.PGame.relabel_moveLeft ** x : PGame xl' xr' : Type u_1 el : xl' ≃ LeftMoves x er : xr' ≃ RightMoves x i : LeftMoves x ⊒ moveLeft (relabel el er) (↑el.symm i) = moveLeft x i ** simp ** Qed
SetTheory.PGame.relabel_moveRight ** x : PGame xl' xr' : Type u_1 el : xl' ≃ LeftMoves x er : xr' ≃ RightMoves x j : RightMoves x ⊒ moveRight (relabel el er) (↑er.symm j) = moveRight x j ** simp ** Qed
SetTheory.PGame.neg_ofLists ** L R : List PGame ⊒ -ofLists L R = ofLists (List.map (fun x => -x) R) (List.map (fun x => -x) L) ** simp only [ofLists, neg_def, List.length_map, List.nthLe_map', eq_self_iff_true, true_and, mk.injEq] ** L R : List PGame ⊒ (HEq (fun j => -List.nthLe R ↑j.down (_ : ↑j.down < List.length R)) fun i => -List.nthLe R ↑i.down (_ : ↑i.down < List.length R)) ∧ HEq (fun i => -List.nthLe L ↑i.down (_ : ↑i.down < List.length L)) fun j => -List.nthLe L ↑j.down (_ : ↑j.down < List.length L) ** constructor ** case right L R : List PGame ⊒ HEq (fun i => -List.nthLe L ↑i.down (_ : ↑i.down < List.length L)) fun j => -List.nthLe L ↑j.down (_ : ↑j.down < List.length L) ** apply hfunext ** case right.hΞ± L R : List PGame ⊒ ULift.{u_1, 0} (Fin (List.length L)) = ULift.{u_1, 0} (Fin (List.length (List.map (fun x => -x) L))) ** simp ** case right.h L R : List PGame ⊒ βˆ€ (a : ULift.{u_1, 0} (Fin (List.length L))) (a' : ULift.{u_1, 0} (Fin (List.length (List.map (fun x => -x) L)))), HEq a a' β†’ HEq (-List.nthLe L ↑a.down (_ : ↑a.down < List.length L)) (-List.nthLe L ↑a'.down (_ : ↑a'.down < List.length L)) ** intro a a' ha ** case right.h L R : List PGame a : ULift.{u_1, 0} (Fin (List.length L)) a' : ULift.{u_1, 0} (Fin (List.length (List.map (fun x => -x) L))) ha : HEq a a' ⊒ HEq (-List.nthLe L ↑a.down (_ : ↑a.down < List.length L)) (-List.nthLe L ↑a'.down (_ : ↑a'.down < List.length L)) ** congr 2 ** case right.h.h.e_a.e_n L R : List PGame a : ULift.{u_1, 0} (Fin (List.length L)) a' : ULift.{u_1, 0} (Fin (List.length (List.map (fun x => -x) L))) ha : HEq a a' ⊒ ↑a.down = ↑a'.down ** have : βˆ€ {m n} (_ : m = n) {b : ULift (Fin m)} {c : ULift (Fin n)} (_ : HEq b c), (b.down : β„•) = ↑c.down := by rintro m n rfl b c simp only [heq_eq_eq] rintro rfl rfl ** case right.h.h.e_a.e_n L R : List PGame a : ULift.{u_1, 0} (Fin (List.length L)) a' : ULift.{u_1, 0} (Fin (List.length (List.map (fun x => -x) L))) ha : HEq a a' this : βˆ€ {m n : β„•}, m = n β†’ βˆ€ {b : ULift.{?u.106967, 0} (Fin m)} {c : ULift.{?u.106967, 0} (Fin n)}, HEq b c β†’ ↑b.down = ↑c.down ⊒ ↑a.down = ↑a'.down ** exact this (List.length_map _ _).symm ha ** L R : List PGame a : ULift.{u_1, 0} (Fin (List.length L)) a' : ULift.{u_1, 0} (Fin (List.length (List.map (fun x => -x) L))) ha : HEq a a' ⊒ βˆ€ {m n : β„•}, m = n β†’ βˆ€ {b : ULift.{?u.106967, 0} (Fin m)} {c : ULift.{?u.106967, 0} (Fin n)}, HEq b c β†’ ↑b.down = ↑c.down ** rintro m n rfl b c ** L R : List PGame a : ULift.{u_1, 0} (Fin (List.length L)) a' : ULift.{u_1, 0} (Fin (List.length (List.map (fun x => -x) L))) ha : HEq a a' m : β„• b c : ULift.{?u.106967, 0} (Fin m) ⊒ HEq b c β†’ ↑b.down = ↑c.down ** simp only [heq_eq_eq] ** L R : List PGame a : ULift.{u_1, 0} (Fin (List.length L)) a' : ULift.{u_1, 0} (Fin (List.length (List.map (fun x => -x) L))) ha : HEq a a' m : β„• b c : ULift.{?u.106967, 0} (Fin m) ⊒ b = c β†’ ↑b.down = ↑c.down ** rintro rfl ** L R : List PGame a : ULift.{u_1, 0} (Fin (List.length L)) a' : ULift.{u_1, 0} (Fin (List.length (List.map (fun x => -x) L))) ha : HEq a a' m : β„• b : ULift.{?u.106967, 0} (Fin m) ⊒ ↑b.down = ↑b.down ** rfl ** Qed
SetTheory.PGame.isOption_neg ** x y : PGame ⊒ IsOption x (-y) ↔ IsOption (-x) y ** rw [IsOption_iff, IsOption_iff, or_comm] ** x y : PGame ⊒ ((βˆƒ i, x = moveRight (-y) i) ∨ βˆƒ i, x = moveLeft (-y) i) ↔ (βˆƒ i, -x = moveLeft y i) ∨ βˆƒ i, -x = moveRight y i ** cases y ** case mk.hβ‚‚ x : PGame α✝ β✝ : Type u_1 a✝¹ : α✝ β†’ PGame a✝ : β✝ β†’ PGame ⊒ (βˆƒ i, x = moveLeft (-mk α✝ β✝ a✝¹ a✝) i) ↔ βˆƒ i, -x = moveRight (mk α✝ β✝ a✝¹ a✝) i ** apply exists_congr ** case mk.hβ‚‚.h x : PGame α✝ β✝ : Type u_1 a✝¹ : α✝ β†’ PGame a✝ : β✝ β†’ PGame ⊒ βˆ€ (a : LeftMoves (-mk α✝ β✝ a✝¹ a✝)), x = moveLeft (-mk α✝ β✝ a✝¹ a✝) a ↔ -x = moveRight (mk α✝ β✝ a✝¹ a✝) a ** intro ** case mk.hβ‚‚.h x : PGame α✝ β✝ : Type u_1 a✝² : α✝ β†’ PGame a✝¹ : β✝ β†’ PGame a✝ : LeftMoves (-mk α✝ β✝ a✝² a✝¹) ⊒ x = moveLeft (-mk α✝ β✝ a✝² a✝¹) a✝ ↔ -x = moveRight (mk α✝ β✝ a✝² a✝¹) a✝ ** rw [neg_eq_iff_eq_neg] ** case mk.hβ‚‚.h x : PGame α✝ β✝ : Type u_1 a✝² : α✝ β†’ PGame a✝¹ : β✝ β†’ PGame a✝ : LeftMoves (-mk α✝ β✝ a✝² a✝¹) ⊒ x = moveLeft (-mk α✝ β✝ a✝² a✝¹) a✝ ↔ x = -moveRight (mk α✝ β✝ a✝² a✝¹) a✝ ** rfl ** Qed
SetTheory.PGame.isOption_neg_neg ** x y : PGame ⊒ IsOption (-x) (-y) ↔ IsOption x y ** rw [isOption_neg, neg_neg] ** Qed