English
The operation Hom₂ on ModuleCat recovers exactly the original bilinear map when mapped back via ofHom₂.
Русский
Операция Hom₂ восстанавливает исходную билинейную карту при обратном отображении через ofHom₂.
LaTeX
$$$\mathrm{hom}_2(\mathrm{ofHom_2}(f)) = f$.$$
Lean4
/-- Turn a homomorphism into a bilinear map. -/
@[simps!]
def hom₂
{M N P : ModuleCat.{u} R}
-- We write `Hom` instead of `M ⟶ (of R (N ⟶ P))`, otherwise dot notation breaks
-- since it is expecting the type of `f` to be `ModuleCat.Hom`, not `Quiver.Hom`.
(f : Hom M (of R (N ⟶ P))) : M →ₗ[R] N →ₗ[R] P :=
Hom.hom (by convert (f ≫ ofHom homLinearEquiv.toLinearMap))