Truncations for a t-structure #
Let t be a t-structure on a (pre)triangulated category C.
In this file, for any n : ℤ, we introduce the truncation functors
t.truncLE n : C ⥤ C and t.truncGT n : C ⥤ C, as variants of the functors
t.truncLT n : C ⥤ C and t.truncGE n : C ⥤ C introduced in the file
Mathlib/CategoryTheory/Triangulated/TStucture/TruncLTGE.lean.
Given a t-structure t on a pretriangulated category C and n : ℤ, this
is the ≤ n-truncation functor. See also the natural transformation truncLEι.
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Given a t-structure t on a pretriangulated category C and n : ℤ, this
is the > n-truncation functor. See also the natural transformation truncGTπ.
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The isomorphism t.truncLE a ≅ t.truncLT b when a + 1 = b.
Equations
- t.truncLEIsoTruncLT a b h = CategoryTheory.eqToIso ⋯
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The isomorphism t.truncGT a ≅ t.truncGE b when a + 1 = b.
Equations
- t.truncGTIsoTruncGE a b h = CategoryTheory.eqToIso ⋯
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The natural transformation t.truncLE n ⟶ 𝟭 C when t is a t-structure
on a category C and n : ℤ.
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The natural transformation t.truncLE a ⟶ t.truncLE b when a ≤ b.
Equations
- t.natTransTruncLEOfLE a b h = t.natTransTruncLTOfLE (a + 1) (b + 1) ⋯
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The natural transformation 𝟭 C ⟶ t.truncGT n when t is a t-structure
on a category C and n : ℤ.
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The connecting homomorphism (t.truncGE b).obj X ⟶ ((t.truncLE a).obj X)⟦1⟧
when a + 1 = b, as a natural transformation.
Equations
- t.truncGEδLE a b h = CategoryTheory.CategoryStruct.comp (t.truncGEδLT b) (CategoryTheory.Functor.whiskerRight (t.truncLEIsoTruncLT a b h).inv (CategoryTheory.shiftFunctor C 1))
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The distinguished triangle (t.truncLE a).obj A ⟶ A ⟶ (t.truncGE b).obj A ⟶ ...
as a functor C ⥤ Triangle C when t is a t-structure on a pretriangulated
category C and a + 1 = b.
Equations
- t.triangleLEGE a b h = CategoryTheory.Pretriangulated.Triangle.functorMk (t.truncLEι a) (t.truncGEπ b) (t.truncGEδLE a b h)
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The natural isomorphism of triangles t.triangleLEGE a b h ≅ t.triangleLTGE b
when a + 1 = b.
Equations
- One or more equations did not get rendered due to their size.
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The connecting homomorphism (t.truncGT n).obj X ⟶ ((t.truncLE n).obj X)⟦1⟧
for n : ℤ, as a natural transformation.
Equations
- t.truncGTδLE n = CategoryTheory.CategoryStruct.comp (t.truncGTIsoTruncGE n (n + 1) ⋯).hom (t.truncGEδLE n (n + 1) ⋯)
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The distinguished triangle (t.truncLE n).obj A ⟶ A ⟶ (t.truncGT n).obj A ⟶ ...
as a functor C ⥤ Triangle C when t is a t-structure on a pretriangulated
category C and n : ℤ.
Equations
- t.triangleLEGT n = CategoryTheory.Pretriangulated.Triangle.functorMk (t.truncLEι n) (t.truncGTπ n) (t.truncGTδLE n)
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The natural isomorphism t.triangleLEGT a ≅ t.triangleLEGE a b h
when a + 1 = b.
Equations
- One or more equations did not get rendered due to their size.
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Constructor for morphisms to (t.truncLE n).obj Y.
Equations
- t.liftTruncLE f n = ⋯.choose
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Constructor for morphisms from (t.truncGT n₀).obj Y.
Equations
- t.descTruncGT f n₀ n₁ h = ⋯.choose
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The composition t.truncGE a ⋙ t.truncGE b.
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The composition t.truncLE b ⋙ t.truncGE a.
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The natural isomorphism t.truncGELE a b ≅ t.truncGELT a b' when b + 1 = b'.
Equations
- t.truncGELEIsoTruncGELT a b b' hb' = CategoryTheory.Functor.isoWhiskerRight (t.truncLEIsoTruncLT b b' hb') (t.truncGE a)
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The natural isomorphism t.truncGELE a b ≅ t.truncLEGE a b.
Equations
- t.truncGELEIsoLEGE a b = t.truncGELTIsoLTGE a (b + 1)