English
For sq between f and f' and sq' between f' and f'', the kernelSubobjectMap respects composition: kernelSubobjectMap ((CategoryTheory.instCategoryArrow C).comp sq sq') = kernelSubobjectMap sq ≫ kernelSubobjectMap sq'.
Русский
Карта kernelSubobjectMap сохраняет композицию квадратов.
LaTeX
$$$$ kernelSubobjectMap ((CategoryTheory.instCategoryArrow C).comp \\; sq \\; sq') = kernelSubobjectMap\\; sq \\; \\gg kernelSubobjectMap\\; sq' $$$$
Lean4
@[reassoc (attr := simp), elementwise (attr := simp)]
theorem kernelSubobjectMap_arrow (sq : Arrow.mk f ⟶ Arrow.mk f') :
kernelSubobjectMap sq ≫ (kernelSubobject f').arrow = (kernelSubobject f).arrow ≫ sq.left := by
simp [kernelSubobjectMap]