The ground field k, viewed as a one-dimensional vector space, is a simple
object in FGModuleCat k: every monomorphism into it from a nonzero object is an iso.
An object X of FGModuleCat k that is not categorically zero is nontrivial
as a vector space, i.e. it contains a nonzero element.
The morphism k ⟶ X sending 1 to a nonzero vector v ∈ X is itself nonzero
in FGModuleCat k.
The morphism k ⟶ X sending 1 to a nonzero vector v ∈ X is a monomorphism
in FGModuleCat k, since c ↦ c • v is injective when v ≠ 0.
Every simple object X in FGModuleCat k is isomorphic to the ground field k,
since a nonzero vector spans a one-dimensional subspace which then forces an iso.
Instances For
The additive map sending a k-linear map X →ₗ[k] Y to its packaging as
a morphism X ⟶ Y in FGModuleCat k.
Instances For
FGModuleCat k is a semisimple category: every finite-dimensional k-vector
space splits as a direct sum of dim_k(X) copies of the simple object k.
FGModuleCat k has finitely many isomorphism classes of simple objects, in fact
exactly one: every simple object is isomorphic to the ground field k.
Vec k = FGModuleCat k is a fusion category over k: it is a finite, semisimple,
rigid k-linear tensor category whose unit has endomorphism algebra k.