Upgrading a killing diagram to a nonempty one #
Schur vanishing is upward closed, and the empty diagram is below every diagram, so a killed object is killed at some diagram with at least one cell.
A diagram with no cells is the empty diagram.
theorem
RS.exists_killer_card_ne_zero
{A : Type u}
[CategoryTheory.Category.{v, u} A]
[CategoryTheory.MonoidalCategory A]
[CategoryTheory.SymmetricCategory A]
[CategoryTheory.Preadditive A]
[CategoryTheory.Linear ℂ A]
[CategoryTheory.MonoidalPreadditive A]
[CategoryTheory.MonoidalLinear ℂ A]
(P : SchurPackage)
{X : A}
{lam : YoungDiagram}
(h : SchurKilled P X lam)
:
∃ (mu : YoungDiagram), mu.card ≠ 0 ∧ SchurKilled P X mu
A killed object is killed at a nonempty diagram.