English
There is an isomorphism between the principalOpen presheaf and the right Kan extension along principals.
Русский
Существует изоморфизм между пресешефом principalOpen и правым кан-расширением вдоль princip als.
LaTeX
$$$\\operatorname{principalOpen} \\cong \\mathrm{principalsKanExtension}(F)$$$
Lean4
/-- The localization of a presheaf of `CommRing`s with respect to a `SubmonoidPresheaf`. -/
protected noncomputable def localizationPresheaf : X.Presheaf CommRingCat
where
obj U := CommRingCat.of <| Localization (G.obj U)
map {_ _} i := CommRingCat.ofHom <| IsLocalization.map _ (F.map i).hom (G.map i)
map_id
U := by
simp_rw [F.map_id]
ext x
exact IsLocalization.map_id x
map_comp {U V W} i
j := by
delta CommRingCat.ofHom CommRingCat.of Bundled.of
simp_rw [F.map_comp]
ext : 1
dsimp
rw [IsLocalization.map_comp_map]