English
With HasEqualizer f g, the inverse of the equalizerSubobjectIso f g composed with the equalizerSubobject f g arrow recovers the equalizer morphism: (equalizerSubobjectIso f g).inv ≫ (equalizerSubobject f g).arrow = equalizer.ι f g.
Русский
При наличии HasEqualizer f g обратная часть изоморфизма equalizerSubobject f g, композиция с стрелой подобъекта равенства возвращает исходную стрелу эквалайзера.
LaTeX
$$$$(equalizerSubobjectIso f g).inv \\circ (equalizerSubobject f g).arrow = equalizer.ι f g$$$$
Lean4
@[reassoc (attr := simp)]
theorem equalizerSubobject_arrow' :
(equalizerSubobjectIso f g).inv ≫ (equalizerSubobject f g).arrow = equalizer.ι f g := by
simp [equalizerSubobjectIso]