The stupid truncation of homological complexes #
Given an embedding e : c.Embedding c' of complex shapes, we define
a functor stupidTruncFunctor : HomologicalComplex C c' ⥤ HomologicalComplex C c'
which sends K to K.stupidTrunc e which is defined as (K.restriction e).extend e.
The stupid truncation of a complex K : HomologicalComplex C c' relatively to
an embedding e : c.Embedding c' of complex shapes.
Equations
- K.stupidTrunc e = (K.restriction e).extend e
Instances For
The isomorphism (K.stupidTrunc e).X i' ≅ K.X i' when i is in the image of e.f.
Equations
- K.stupidTruncXIso e hi' = (K.restriction e).extendXIso e hi' ≪≫ CategoryTheory.eqToIso ⋯
Instances For
The morphism K.stupidTrunc e ⟶ L.stupidTrunc e induced by a morphism K ⟶ L.
Equations
Instances For
Auxiliary definition for ιStupidTrunc.
Equations
- K.ιStupidTruncf e i' = if h : ∃ (i : ι), e.f i = i' then (K.stupidTruncXIso e ⋯).hom else 0
Instances For
The monomorphism K.stupidTrunc e ⟶ K when the embedding e of complex shapes
satisfies e.IsTruncGE.
Equations
- K.ιStupidTrunc e = { f := K.ιStupidTruncf e, comm' := ⋯ }
Instances For
Auxiliary definition for πStupidTrunc.
Equations
- K.πStupidTruncf e i' = if h : ∃ (i : ι), e.f i = i' then (K.stupidTruncXIso e ⋯).inv else 0
Instances For
The epimorphism K ⟶ K.stupidTrunc e when the embedding e of complex shapes
satisfies e.IsTruncLE.
Equations
- K.πStupidTrunc e = { f := K.πStupidTruncf e, comm' := ⋯ }
Instances For
The stupid truncation functor HomologicalComplex C c' ⥤ HomologicalComplex C c'
given by an embedding e : Embedding c c' of complex shapes.
Equations
- One or more equations did not get rendered due to their size.
Instances For
When e : Embedding c c' satisfies [e.IsTruncGE], this is
the natural transformation K.ιStupidTrunc e : K.stupidTrunc e ⟶ K
for all K : HomologicalComplex C c'.
Equations
- e.ιStupidTruncNatTrans C = { app := fun (K : HomologicalComplex C c') => K.ιStupidTrunc e, naturality := ⋯ }
Instances For
When e : Embedding c c' satisfies [e.IsTruncLE], this is
the natural transformation K.πStupidTrunc e : K ⟶ K.stupidTrunc e
for all K : HomologicalComplex C c'.
Equations
- e.πStupidTruncNatTrans C = { app := fun (K : HomologicalComplex C c') => K.πStupidTrunc e, naturality := ⋯ }