English
For a natural transformation α: F ⇒ G, its evaluation at X is an R-linear map α_X: F.obj X → G.obj X.
Русский
Для натурального преобразования α: F ⇒ G его значение на X задаёт линейный по R гомоморфизм α_X: F.obj X → G.obj X.
LaTeX
$$$\\alpha_X: F.obj X \\to G.obj X$ is R-linear in α.$$
Lean4
instance functorCategoryLinear : Linear R (C ⥤ D)
where
homModule F
G :=
{ smul := fun r α =>
{ app := fun X => r • α.app X
naturality := by
intros
rw [comp_smul, smul_comp, α.naturality] }
one_smul := by
intros
ext
apply one_smul
zero_smul := by
intros
ext
apply zero_smul
smul_zero := by
intros
ext
apply smul_zero
add_smul := by
intros
ext
apply add_smul
smul_add := by
intros
ext
apply smul_add
mul_smul := by
intros
ext
apply mul_smul }
smul_comp := by
intros
ext
apply smul_comp
comp_smul := by
intros
ext
apply comp_smul