feat(types/pointed): change definition of loop space
This commit is contained in:
Floris van Doorn
Leonardo de Moura
parent
d402b67d25
commit
47be1e3a15
6 changed files with 89 additions and 46 deletions
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@ -98,8 +98,10 @@ namespace sphere
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pmap.mk (λa, merid a ⬝ (merid base)⁻¹) !con.right_inv
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definition surf {n : ℕ} : Ω[n] S. n :=
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nat.rec_on n (by esimp [Iterated_loop_space]; exact base)
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(by intro n s;exact apn n (equator n) s)
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nat.rec_on n (proof base qed)
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(begin intro m s, refine cast _ (apn m (equator m) s),
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exact ap Pointed.carrier !loop_space_succ_eq_in⁻¹ end)
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definition bool_of_sphere : S 0 → bool :=
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susp.rec ff tt (λx, empty.elim x)
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@ -120,12 +122,20 @@ namespace sphere
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definition sphere_eq_bool_pointed : S. 0 = Bool :=
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Pointed_eq sphere_equiv_bool idp
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-- TODO: the commented-out part makes the forward function below "apn _ surf"
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definition pmap_sphere (A : Pointed) (n : ℕ) : map₊ (S. n) A ≃ Ω[n] A :=
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begin
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revert A, induction n with n IH,
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{ intro A, rewrite [sphere_eq_bool_pointed], apply pmap_bool_equiv},
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{ intro A, transitivity _, apply susp_adjoint_loop (S. n) A, apply IH}
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end -- can we prove this in such a way that the function from left to right is apn _ surf?
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-- fapply equiv_change_fun,
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-- {
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revert A, induction n with n IH: intro A,
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{ rewrite [sphere_eq_bool_pointed], apply pmap_bool_equiv},
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{ refine susp_adjoint_loop (S. n) A ⬝e !IH ⬝e _, rewrite [loop_space_succ_eq_in]}
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-- },
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-- { intro f, exact apn n f surf},
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-- { revert A, induction n with n IH: intro A f,
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-- { exact sorry},
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-- { exact sorry}}
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end
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protected definition elim {n : ℕ} {P : Pointed} (p : Ω[n] P) : map₊ (S. n) P :=
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to_inv !pmap_sphere p
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@ -287,7 +287,7 @@ namespace equiv
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protected definition trans [trans] (f : A ≃ B) (g : B ≃ C) : A ≃ C :=
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equiv.mk (g ∘ f) !is_equiv_compose
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infixl `⬝e`:75 := equiv.trans
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infixl ` ⬝e `:75 := equiv.trans
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postfix [parsing_only] `⁻¹ᵉ`:(max + 1) := equiv.symm
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-- notation for inverse which is not overloaded
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abbreviation erfl [constructor] := @equiv.refl
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@ -181,6 +181,9 @@ namespace iff
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definition rfl {a : Type} : a ↔ a :=
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refl a
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definition iff_of_eq (a b : Type) (p : a = b) : a ↔ b :=
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eq.rec rfl p
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definition trans (H₁ : a ↔ b) (H₂ : b ↔ c) : a ↔ c :=
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intro
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(assume Ha, elim_left H₂ (elim_left H₁ Ha))
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@ -49,6 +49,7 @@ namespace is_trunc
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definition succ_le_succ {n m : trunc_index} (H : n ≤ m) : n.+1 ≤ m.+1 := H
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definition le_of_succ_le_succ {n m : trunc_index} (H : n.+1 ≤ m.+1) : n ≤ m := H
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definition minus_two_le (n : trunc_index) : -2 ≤ n := star
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definition le.refl (n : trunc_index) : n ≤ n := by induction n with n IH; exact star; exact IH
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definition empty_of_succ_le_minus_two {n : trunc_index} (H : n .+1 ≤ -2) : empty := H
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end trunc_index
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definition trunc_index.of_nat [coercion] [reducible] (n : nat) : trunc_index :=
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@ -6,7 +6,7 @@ Authors: Jakob von Raumer, Floris van Doorn
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Ported from Coq HoTT
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-/
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import arity .eq .bool .unit .sigma
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import arity .eq .bool .unit .sigma .nat.basic
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open is_trunc eq prod sigma nat equiv option is_equiv bool unit
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structure pointed [class] (A : Type) :=
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@ -66,12 +66,9 @@ namespace pointed
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definition Loop_space [reducible] [constructor] (A : Type*) : Type* :=
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pointed.mk' (point A = point A)
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-- definition Iterated_loop_space : Type* → ℕ → Type*
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-- | Iterated_loop_space A 0 := A
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-- | Iterated_loop_space A (n+1) := Iterated_loop_space (Loop_space A) n
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definition Iterated_loop_space [unfold 1] [reducible] (n : ℕ) (A : Type*) : Type* :=
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nat.rec_on n (λA, A) (λn IH A, IH (Loop_space A)) A
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definition Iterated_loop_space [unfold 1] [reducible] : ℕ → Type* → Type*
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| Iterated_loop_space 0 X := X
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| Iterated_loop_space (n+1) X := Loop_space (Iterated_loop_space n X)
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prefix `Ω`:(max+5) := Loop_space
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notation `Ω[`:95 n:0 `] `:0 A:95 := Iterated_loop_space n A
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@ -183,12 +180,6 @@ namespace pointed
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{ esimp, exact !con.left_inv⁻¹}},
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end
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-- definition Loop_space_functor (f : A →* B) : Ω A →* Ω B :=
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-- begin
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-- fapply pmap.mk,
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-- { intro p, exact ap f p},
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-- end
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-- set_option pp.notation false
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-- definition pmap_equiv_right (A : Type*) (B : Type)
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-- : (Σ(b : B), map₊ A (pointed.Mk b)) ≃ (A → B) :=
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@ -217,17 +208,59 @@ namespace pointed
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{ esimp, exact !con.left_inv⁻¹}},
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end
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definition apn [unfold 3] (n : ℕ) (f : map₊ A B) : Ω[n] A →* Ω[n] B :=
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definition ap1 [constructor] (f : A →* B) : Ω A →* Ω B :=
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begin
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revert A B f, induction n with n IH,
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{ intros A B f, exact f},
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{ intros A B f, esimp, apply IH (Ω A),
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{ esimp, fconstructor,
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intro q, refine !respect_pt⁻¹ ⬝ ap f q ⬝ !respect_pt,
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esimp, apply con.left_inv}}
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fconstructor,
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{ intro p, exact !respect_pt⁻¹ ⬝ ap f p ⬝ !respect_pt},
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{ esimp, apply con.left_inv}
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end
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definition ap1 [constructor] (f : A →* B) : Ω A →* Ω B := apn (succ 0) f
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definition apn [unfold 3] (n : ℕ) (f : map₊ A B) : Ω[n] A →* Ω[n] B :=
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begin
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induction n with n IH,
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{ exact f},
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{ esimp [Iterated_loop_space], exact ap1 IH}
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end
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variable (A)
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definition loop_space_succ_eq_in (n : ℕ) : Ω[succ n] A = Ω[n] (Ω A) :=
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begin
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induction n with n IH,
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{ reflexivity},
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{ exact ap Loop_space IH}
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end
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definition loop_space_add (n m : ℕ) : Ω[n] (Ω[m] A) = Ω[m+n] (A) :=
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begin
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induction n with n IH,
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{ reflexivity},
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{ exact ap Loop_space IH}
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end
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definition loop_space_succ_eq_out (n : ℕ) : Ω[succ n] A = Ω(Ω[n] A) :=
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idp
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variable {A}
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definition loop_space_loop_irrel (p : point A = point A) : Ω(Pointed.mk p) = Ω[2] A :=
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begin
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intros, fapply Pointed_eq,
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{ esimp, transitivity _,
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apply eq_equiv_fn_eq_of_equiv (equiv_eq_closed_right _ p⁻¹),
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esimp, apply eq_equiv_eq_closed, apply con.right_inv, apply con.right_inv},
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{ esimp, apply con.left_inv}
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end
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definition iterated_loop_space_loop_irrel (n : ℕ) (p : point A = point A)
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: Ω[succ n](Pointed.mk p) = Ω[succ (succ n)] A :> Pointed :=
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calc
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Ω[succ n](Pointed.mk p) = Ω[n](Ω (Pointed.mk p)) : loop_space_succ_eq_in
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... = Ω[n] (Ω[2] A) : loop_space_loop_irrel
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... = Ω[2+n] A : loop_space_add
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... = Ω[n+2] A : add.comm
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-- TODO:
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-- definition apn_compose (n : ℕ) (g : B →* C) (f : A →* B) : apn n (g ∘* f) ~* apn n g ∘* apn n f :=
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-- _
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definition ap1_compose (g : B →* C) (f : A →* B) : ap1 (g ∘* f) ~* ap1 g ∘* ap1 f :=
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begin
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@ -138,30 +138,26 @@ namespace is_trunc
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induction p, apply Hp
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end
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theorem is_hprop_iff_is_contr {A : Type} (a : A) :
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is_hprop A ↔ is_contr A :=
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iff.intro (λH, is_contr.mk a (is_hprop.elim a)) _
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theorem is_trunc_succ_iff_is_trunc_loop (A : Type) (Hn : -1 ≤ n) :
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is_trunc (n.+1) A ↔ Π(a : A), is_trunc n (a = a) :=
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iff.intro _ (is_trunc_succ_of_is_trunc_loop Hn)
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--set_option pp.all true
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theorem is_trunc_iff_is_contr_loop_succ (n : ℕ) (A : Type)
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: is_trunc n A ↔ Π(a : A), is_contr (Ω[succ n](Pointed.mk a)) :=
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begin
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revert A, induction n with n IH,
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{ intros, esimp [Iterated_loop_space], apply iff.intro,
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{ intros H a, apply is_contr.mk idp, apply is_hprop.elim},
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{ intro H, apply is_hset_of_axiom_K, intros, apply is_hprop.elim}},
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{ intros, transitivity _, apply @is_trunc_succ_iff_is_trunc_loop n, constructor,
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apply iff.pi_iff_pi, intros,
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transitivity _, apply IH,
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assert H : Πp : a = a, Ω(Pointed.mk p) = Ω(Pointed.mk (idpath a)),
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{ intros, fapply Pointed_eq,
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{ esimp, transitivity _,
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apply eq_equiv_fn_eq_of_equiv (equiv_eq_closed_right _ p⁻¹),
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esimp, apply eq_equiv_eq_closed, apply con.right_inv, apply con.right_inv},
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{ esimp, apply con.left_inv}},
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transitivity _,
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apply iff.pi_iff_pi, intro p,
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rewrite [↑Iterated_loop_space,H],
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apply iff.refl,
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{ intro A, esimp [Iterated_loop_space], transitivity _,
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{ apply is_trunc_succ_iff_is_trunc_loop, apply le.refl},
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{ apply iff.pi_iff_pi, intro a, esimp, apply is_hprop_iff_is_contr, reflexivity}},
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{ intro A, esimp [Iterated_loop_space],
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transitivity _, apply @is_trunc_succ_iff_is_trunc_loop @n, esimp, constructor,
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apply iff.pi_iff_pi, intro a, transitivity _, apply IH,
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transitivity _, apply iff.pi_iff_pi, intro p,
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rewrite [iterated_loop_space_loop_irrel n p], apply iff.refl, esimp,
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apply iff.imp_iff, reflexivity}
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end
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