English
The pullback of the open immersions awayι at f and g is isomorphic to the affine open D_+(fg) lying over the sum of degrees m and m'.
Русский
Вычисление вытяжки открытых вложений Away: равенство близкое к открытому D_+(fg) над суммой степеней m и m'.
LaTeX
$$pullbackAwayιIso 𝒜 f_deg hm g_deg hm' hx ≅ Spec (.of <| Away 𝒜 x)$$
Lean4
@[reassoc]
theorem SpecMap_awayMap_awayι :
Spec.map (CommRingCat.ofHom (awayMap 𝒜 g_deg hx)) ≫ awayι 𝒜 f f_deg hm =
awayι 𝒜 x (hx ▸ SetLike.mul_mem_graded f_deg g_deg) (hm.trans_le (m.le_add_right m')) :=
by
rw [awayι, awayι, Iso.eq_inv_comp, basicOpenIsoSpec_hom, basicOpenToSpec_SpecMap_awayMap_assoc, ←
basicOpenIsoSpec_hom _ _ f_deg hm, Iso.hom_inv_id_assoc, Scheme.homOfLE_ι]