Quotients when every nonzero map is irreducible #
theorem
MagnitudeConjecture.CategoricalIrreducible.radical_eq_top_of_no_reverse
(k : Type u)
[Field k]
{C : Type v}
[CategoryTheory.Category.{w, v} C]
[CategoryTheory.Preadditive C]
[CategoryTheory.Linear k C]
(X Y : C)
(h : ∀ (g : Y ⟶ X), g = 0)
:
radical k X Y = ⊤
No reverse maps implies that every forward map is radical.
theorem
MagnitudeConjecture.CategoricalIrreducible.radicalSquare_eq_bot_of_all_nonzero_irreducible
(k : Type u)
[Field k]
{C : Type v}
[CategoryTheory.Category.{w, v} C]
[CategoryTheory.Preadditive C]
[CategoryTheory.Linear k C]
(X Y : C)
(hi : ∀ (f : X ⟶ Y), f ≠ 0 → QuotientSubmoduleEquidistribution.IsIrreducibleMorphism f)
:
radicalSquare k X Y = ⊥
A Hom space consisting of zero and irreducible maps has zero radical square.
def
MagnitudeConjecture.CategoricalIrreducible.spaceEquivHom
(k : Type u)
[Field k]
{C : Type v}
[CategoryTheory.Category.{w, v} C]
[CategoryTheory.Preadditive C]
[CategoryTheory.Linear k C]
(X Y : C)
(hr : radical k X Y = ⊤)
(hs : radicalSquare k X Y = ⊥)
:
Space k X Y ≃ₗ[k] X ⟶ Y
If the radical is all of Hom and its square is zero, the intrinsic irreducible quotient is linearly equivalent to Hom itself.