319 lines
11 KiB
Text
319 lines
11 KiB
Text
/-
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Copyright (c) 2017 Floris van Doorn and Ulrik Buchholtz. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Floris van Doorn, Ulrik Buchholtz
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Truncatedness and truncation of spectra
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-/
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import .spectrum .EM
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namespace int
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-- TODO move this
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open nat algebra
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section
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private definition maxm2_le.lemma₁ {n k : ℕ} : n+(1:int) + -[1+ k] ≤ n :=
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le.intro (
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calc n + 1 + -[1+ k] + k
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= n + 1 + (-(k + 1)) + k : by reflexivity
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... = n + 1 + (-1 - k) + k : by krewrite (neg_add_rev k 1)
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... = n + 1 + (-1 - k + k) : add.assoc
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... = n + 1 + (-1 + -k + k) : by reflexivity
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... = n + 1 + (-1 + (-k + k)) : add.assoc
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... = n + 1 + (-1 + 0) : add.left_inv
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... = n + (1 + (-1 + 0)) : add.assoc
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... = n : int.add_zero)
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private definition maxm2_le.lemma₂ {n : ℕ} {k : ℤ} : -[1+ n] + 1 + k ≤ k :=
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le.intro (
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calc -[1+ n] + 1 + k + n
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= - (n + 1) + 1 + k + n : by reflexivity
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... = -n - 1 + 1 + k + n : by rewrite (neg_add n 1)
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... = -n + (-1 + 1) + k + n : by krewrite (int.add_assoc (-n) (-1) 1)
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... = -n + 0 + k + n : add.left_inv 1
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... = -n + k + n : int.add_zero
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... = k + -n + n : int.add_comm
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... = k + (-n + n) : int.add_assoc
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... = k + 0 : add.left_inv n
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... = k : int.add_zero)
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open trunc_index
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definition maxm2_le (n k : ℤ) : maxm2 (n+1+k) ≤ (maxm1m1 n).+1+2+(maxm1m1 k) :=
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begin
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rewrite [-(maxm1_eq_succ n)],
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induction n with n n,
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{ induction k with k k,
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{ induction k with k IH,
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{ apply le.tr_refl },
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{ exact succ_le_succ IH } },
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{ exact trunc_index.le_trans (maxm2_monotone maxm2_le.lemma₁)
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(maxm2_le_maxm1 n) } },
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{ krewrite (add_plus_two_comm -1 (maxm1m1 k)),
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rewrite [-(maxm1_eq_succ k)],
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exact trunc_index.le_trans (maxm2_monotone maxm2_le.lemma₂)
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(maxm2_le_maxm1 k) }
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end
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end
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end int
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open int trunc eq is_trunc lift unit pointed equiv is_equiv algebra EM
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namespace spectrum
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definition ptrunc_maxm2_change_int {k l : ℤ} (p : k = l) (X : Type*)
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: ptrunc (maxm2 k) X ≃* ptrunc (maxm2 l) X :=
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ptrunc_change_index (ap maxm2 p) X
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definition is_trunc_maxm2_change_int {k l : ℤ} (X : pType) (p : k = l)
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: is_trunc (maxm2 k) X → is_trunc (maxm2 l) X :=
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by induction p; exact id
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definition is_trunc_maxm2_loop {k : ℤ} {A : Type*} (H : is_trunc (maxm2 (k+1)) A) :
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is_trunc (maxm2 k) (Ω A) :=
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begin
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induction k with k k,
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apply is_trunc_loop, exact H,
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apply is_contr_loop,
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cases k with k,
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{ exact H },
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{ apply is_trunc_succ, apply is_trunc_succ, exact H }
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end
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definition loop_ptrunc_maxm2_pequiv {k : ℤ} {l : ℕ₋₂} (p : maxm2 (k+1) = l) (X : Type*) :
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Ω (ptrunc l X) ≃* ptrunc (maxm2 k) (Ω X) :=
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begin
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induction p,
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induction k with k k,
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{ exact loop_ptrunc_pequiv k X },
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{ refine pequiv_of_is_contr _ _ _ !is_trunc_trunc,
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apply is_contr_loop,
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cases k with k,
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{ change is_set (trunc 0 X), apply _ },
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{ change is_set (trunc -2 X), apply _ }}
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end
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definition ptrunc_elim_phomotopy2 [constructor] (k : ℕ₋₂) {A B : Type*} {f g : A →* B} (H₁ : is_trunc k B)
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(H₂ : is_trunc k B) (p : f ~* g) : @ptrunc.elim k A B H₁ f ~* @ptrunc.elim k A B H₂ g :=
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begin
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fapply phomotopy.mk,
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{ intro x, induction x with a, exact p a },
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{ exact to_homotopy_pt p }
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end
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definition loop_ptrunc_maxm2_pequiv_ptrunc_elim' {k : ℤ} {l : ℕ₋₂} (p : maxm2 (k+1) = l)
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{A B : Type*} (f : A →* B) {H : is_trunc l B} :
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Ω→ (ptrunc.elim l f) ∘* (loop_ptrunc_maxm2_pequiv p A)⁻¹ᵉ* ~*
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@ptrunc.elim (maxm2 k) _ _ (is_trunc_maxm2_loop (is_trunc_of_eq p⁻¹ H)) (Ω→ f) :=
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begin
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induction p, induction k with k k,
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{ refine pwhisker_right _ (ap1_phomotopy _) ⬝* @(ap1_ptrunc_elim k f) H,
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apply ptrunc_elim_phomotopy2, reflexivity },
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{ apply phomotopy_of_is_contr_cod, exact is_trunc_maxm2_loop H }
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end
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definition loop_ptrunc_maxm2_pequiv_ptrunc_elim {k : ℤ} {l : ℕ₋₂} (p : maxm2 (k+1) = l)
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{A B : Type*} (f : A →* B) {H1 : is_trunc ((maxm2 k).+1) B } {H2 : is_trunc l B} :
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Ω→ (ptrunc.elim l f) ∘* (loop_ptrunc_maxm2_pequiv p A)⁻¹ᵉ* ~* ptrunc.elim (maxm2 k) (Ω→ f) :=
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begin
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induction p, induction k with k k: esimp at H1,
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{ refine pwhisker_right _ (ap1_phomotopy _) ⬝* ap1_ptrunc_elim k f,
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apply ptrunc_elim_phomotopy2, reflexivity },
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{ apply phomotopy_of_is_contr_cod }
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end
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definition loop_ptrunc_maxm2_pequiv_ptr {k : ℤ} {l : ℕ₋₂} (p : maxm2 (k+1) = l) (A : Type*) :
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Ω→ (ptr l A) ~* (loop_ptrunc_maxm2_pequiv p A)⁻¹ᵉ* ∘* ptr (maxm2 k) (Ω A) :=
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begin
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induction p, induction k with k k,
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{ exact ap1_ptr k A },
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{ apply phomotopy_pinv_left_of_phomotopy, apply phomotopy_of_is_contr_cod, apply is_trunc_trunc }
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end
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definition is_trunc_of_is_trunc_maxm2 (k : ℤ) (X : Type)
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: is_trunc (maxm2 k) X → is_trunc (max0 k) X :=
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λ H, @is_trunc_of_le X _ _ (maxm2_le_maxm0 k) H
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definition strunc [constructor] (k : ℤ) (E : spectrum) : spectrum :=
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spectrum.MK (λ(n : ℤ), ptrunc (maxm2 (k + n)) (E n))
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(λ(n : ℤ), ptrunc_pequiv_ptrunc (maxm2 (k + n)) (equiv_glue E n)
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⬝e* (loop_ptrunc_maxm2_pequiv (ap maxm2 (add.assoc k n 1)) (E (n+1)))⁻¹ᵉ*)
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definition strunc_change_int [constructor] {k l : ℤ} (E : spectrum) (p : k = l) :
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strunc k E →ₛ strunc l E :=
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begin induction p, reflexivity end
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definition is_strunc [reducible] (k : ℤ) (E : spectrum) : Type :=
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Π (n : ℤ), is_trunc (maxm2 (k + n)) (E n)
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definition is_strunc_change_int {k l : ℤ} (E : spectrum) (p : k = l)
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: is_strunc k E → is_strunc l E :=
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begin induction p, exact id end
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definition is_strunc_of_le {k l : ℤ} (E : spectrum) (H : k ≤ l)
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: is_strunc k E → is_strunc l E :=
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begin
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intro T, intro n, exact is_trunc_of_le (E n)
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(maxm2_monotone (algebra.add_le_add_right H n))
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end
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definition is_strunc_pequiv_closed {k : ℤ} {E F : spectrum} (H : Πn, E n ≃* F n)
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(H2 : is_strunc k E) : is_strunc k F :=
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λn, is_trunc_equiv_closed (maxm2 (k + n)) (H n)
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definition is_strunc_strunc (k : ℤ) (E : spectrum)
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: is_strunc k (strunc k E) :=
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λ n, is_trunc_trunc (maxm2 (k + n)) (E n)
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definition is_strunc_strunc_of_is_strunc (k : ℤ) {l : ℤ} {E : spectrum} (H : is_strunc l E)
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: is_strunc l (strunc k E) :=
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λ n, !is_trunc_trunc_of_is_trunc
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definition str [constructor] (k : ℤ) (E : spectrum) : E →ₛ strunc k E :=
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smap.mk (λ n, ptr (maxm2 (k + n)) (E n))
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abstract begin
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intro n,
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apply psquare_of_phomotopy,
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refine !passoc ⬝* pwhisker_left _ !ptr_natural ⬝* _,
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refine !passoc⁻¹* ⬝* pwhisker_right _ !loop_ptrunc_maxm2_pequiv_ptr⁻¹*,
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end end
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definition strunc_elim [constructor] {k : ℤ} {E F : spectrum} (f : E →ₛ F)
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(H : is_strunc k F) : strunc k E →ₛ F :=
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smap.mk (λn, ptrunc.elim (maxm2 (k + n)) (f n))
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abstract begin
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intro n,
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apply psquare_of_phomotopy,
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symmetry,
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refine !passoc⁻¹* ⬝* pwhisker_right _ !loop_ptrunc_maxm2_pequiv_ptrunc_elim' ⬝* _,
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refine @(ptrunc_elim_ptrunc_functor _ _ _) _ ⬝* _,
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refine _ ⬝* @(ptrunc_elim_pcompose _ _ _) _ _,
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apply is_trunc_maxm2_loop,
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refine is_trunc_of_eq _ (H (n+1)), exact ap maxm2 (add.assoc k n 1)⁻¹,
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apply ptrunc_elim_phomotopy2,
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apply phomotopy_of_psquare,
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apply ptranspose,
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apply smap.glue_square
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end end
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definition strunc_functor [constructor] (k : ℤ) {E F : spectrum} (f : E →ₛ F) :
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strunc k E →ₛ strunc k F :=
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strunc_elim (str k F ∘ₛ f) (is_strunc_strunc k F)
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definition is_strunc_sunit (n : ℤ) : is_strunc n sunit :=
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begin
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intro k, apply is_trunc_lift, apply is_trunc_unit
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end
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open option
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definition is_strunc_add_point_spectrum {X : Type} {Y : X → spectrum} {s₀ : ℤ}
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(H : Πx, is_strunc s₀ (Y x)) : Π(x : X₊), is_strunc s₀ (add_point_spectrum Y x)
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| (some x) := H x
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| none := is_strunc_sunit s₀
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definition is_strunc_EM_spectrum (G : AbGroup)
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: is_strunc 0 (EM_spectrum G) :=
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begin
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intro n, induction n with n n,
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{ -- case ≥ 0
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apply is_trunc_maxm2_change_int (EM G n) (zero_add n)⁻¹,
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apply is_trunc_EM },
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{ change is_contr (EM_spectrum G (-[1+n])),
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induction n with n IH,
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{ -- case = -1
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apply is_contr_loop, exact is_trunc_EM G 0 },
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{ -- case < -1
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apply is_trunc_loop, apply is_trunc_succ, exact IH }}
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end
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definition trivial_shomotopy_group_of_is_strunc (E : spectrum)
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{n k : ℤ} (K : is_strunc n E) (H : n < k)
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: is_contr (πₛ[k] E) :=
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let m := n + (2 - k) in
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have I : m < 2, from
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calc
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m = (2 - k) + n : int.add_comm n (2 - k)
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... < (2 - k) + k : add_lt_add_left H (2 - k)
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... = 2 : sub_add_cancel 2 k,
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@trivial_homotopy_group_of_is_trunc (E (2 - k)) (max0 m) 2
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(is_trunc_of_is_trunc_maxm2 m (E (2 - k)) (K (2 - k)))
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(nat.succ_le_succ (max0_le_of_le (le_sub_one_of_lt I)))
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structure truncspectrum (n : ℤ) :=
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(carrier : spectrum)
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(struct : is_strunc n carrier)
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notation n `-spectrum` := truncspectrum n
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attribute truncspectrum.carrier [coercion]
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definition genspectrum_of_truncspectrum (n : ℤ)
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: n-spectrum → gen_spectrum +ℤ :=
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λ E, truncspectrum.carrier E
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attribute genspectrum_of_truncspectrum [coercion]
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section
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open is_conn
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definition is_conn_maxm1_of_maxm2 (A : Type*) (n : ℤ)
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: is_conn (maxm2 n) A → is_conn (maxm1m1 n).+1 A :=
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begin
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intro H, induction n with n n,
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{ exact H },
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{ exact is_conn_minus_one A (tr pt) }
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end
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definition is_trunc_maxm2_of_maxm1 (A : Type*) (n : ℤ)
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: is_trunc (maxm1m1 n).+1 A → is_trunc (maxm2 n) A :=
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begin
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intro H, induction n with n n,
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{ exact H},
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{ apply is_contr_of_merely_prop,
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{ exact H },
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{ exact tr pt } }
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end
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variables (A : Type*) (n : ℤ) [H : is_conn (maxm2 n) A]
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include H
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definition is_trunc_maxm2_ppi (k l : ℤ) (H3 : l ≤ n+1+k) (P : A → Type*)
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(H2 : Πa, is_trunc (maxm2 l) (P a)) : is_trunc (maxm2 k) (Π*(a : A), P a) :=
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is_trunc_maxm2_of_maxm1 (Π*(a : A), P a) k
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(@is_trunc_ppi_of_is_conn A (maxm1m1 n) (is_conn_maxm1_of_maxm2 A n H) (maxm1m1 k) _
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(le.trans (maxm2_monotone H3) (maxm2_le n k)) P H2)
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definition is_strunc_spi_of_is_conn (k l : ℤ) (H3 : l ≤ n+1+k) (P : A → spectrum)
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(H2 : Πa, is_strunc l (P a)) : is_strunc k (spi A P) :=
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begin
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intro m, unfold spi,
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exact is_trunc_maxm2_ppi A n (k+m) _ (le.trans (add_le_add_right H3 _)
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(le_of_eq (add.assoc (n+1) k m))) (λ a, P a m) (λa, H2 a m)
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end
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end
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definition is_strunc_spi_of_le {A : Type*} (k n : ℤ) (H : n ≤ k) (P : A → spectrum)
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(H2 : Πa, is_strunc n (P a)) : is_strunc k (spi A P) :=
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begin
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assert K : n ≤ -[1+ 0] + 1 + k,
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{ krewrite (int.zero_add k), exact H },
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{ exact @is_strunc_spi_of_is_conn A (-[1+ 0]) (is_conn.is_conn_minus_two A) k _ K P H2 }
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end
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definition is_strunc_spi {A : Type*} (n : ℤ) (P : A → spectrum) (H : Πa, is_strunc n (P a))
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: is_strunc n (spi A P) :=
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is_strunc_spi_of_le n n !le.refl P H
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definition is_strunc_sp_cotensor (n : ℤ) (A : Type*) {Y : spectrum} (H : is_strunc n Y)
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: is_strunc n (sp_cotensor A Y) :=
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is_strunc_pequiv_closed (λn, !pppi_pequiv_ppmap) (is_strunc_spi n (λa, Y) (λa, H))
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definition is_strunc_sp_ucotensor (n : ℤ) (A : Type) {Y : spectrum} (H : is_strunc n Y)
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: is_strunc n (sp_ucotensor A Y) :=
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λk, !pi.is_trunc_arrow
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end spectrum
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