Homological complexes supported in a single degree #
We define single V j c : V ⥤ HomologicalComplex V c
,
which constructs complexes in V
of shape c
, supported in degree j
.
In ChainComplex.toSingle₀Equiv
we characterize chain maps to an
ℕ
-indexed complex concentrated in degree 0; they are equivalent to
{ f : C.X 0 ⟶ X // C.d 1 0 ≫ f = 0 }
.
(This is useful translating between a projective resolution and
an augmented exact complex of projectives.)
The functor V ⥤ HomologicalComplex V c
creating a chain complex supported in a single degree.
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- One or more equations did not get rendered due to their size.
Instances For
The object in degree i
of (single V c h).obj A
is just A
when i = j
.
Equations
- HomologicalComplex.singleObjXIsoOfEq c j A i hi = CategoryTheory.eqToIso ⋯
Instances For
The object in degree j
of (single V c h).obj A
is just A
.
Equations
- HomologicalComplex.singleObjXSelf c j A = HomologicalComplex.singleObjXIsoOfEq c j A j ⋯
Instances For
The natural isomorphism single V c j ⋙ eval V c j ≅ 𝟭 V
.
Equations
Instances For
Equations
- ⋯ = ⋯
Equations
- ⋯ = ⋯
Constructor for morphisms to a single homological complex.
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- One or more equations did not get rendered due to their size.
Instances For
Constructor for morphisms from a single homological complex.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Equations
- ⋯ = ⋯
The functor V ⥤ ChainComplex V ℕ
creating a chain complex supported in degree zero.
Equations
Instances For
Morphisms from an ℕ
-indexed chain complex C
to a single object chain complex with X
concentrated in degree 0
are the same as morphisms f : C.X 0 ⟶ X
such that C.d 1 0 ≫ f = 0
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Morphisms from a single object chain complex with X
concentrated in degree 0
to an ℕ
-indexed chain complex C
are the same as morphisms f : X → C.X 0
.
Equations
- C.fromSingle₀Equiv X = { toFun := fun (f : (ChainComplex.single₀ V).obj X ⟶ C) => f.f 0, invFun := fun (f : X ⟶ C.X 0) => HomologicalComplex.mkHomFromSingle f ⋯, left_inv := ⋯, right_inv := ⋯ }
Instances For
The functor V ⥤ CochainComplex V ℕ
creating a cochain complex supported in degree zero.
Equations
Instances For
Morphisms from a single object cochain complex with X
concentrated in degree 0
to an ℕ
-indexed cochain complex C
are the same as morphisms f : X ⟶ C.X 0
such that f ≫ C.d 0 1 = 0
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Morphisms to a single object cochain complex with X
concentrated in degree 0
to an ℕ
-indexed cochain complex C
are the same as morphisms f : C.X 0 ⟶ X
.
Equations
- C.toSingle₀Equiv X = { toFun := fun (f : C ⟶ (CochainComplex.single₀ V).obj X) => f.f 0, invFun := fun (f : C.X 0 ⟶ X) => HomologicalComplex.mkHomToSingle f ⋯, left_inv := ⋯, right_inv := ⋯ }