Section counts on the blow-up of a surface
OpenOAI.MaximalSeshadri.Geometry.Surface.exceptional_twist_sections_boundsLet be surfaces with ample on and ample on , a configuration of points on , a blow-up of the centre ideal over , and presenting the pullback of the ideal. Then for a line bundle on and , and .
Notation. is cohomologyDimension, the Module.finrank over of , which is 0 for an infinite-dimensional space. PresentsPullbackIdeal I f J ι says that is a monomorphism whose image on affine opens is the extension of along . IsBlowup I π says that pulls back to an invertible ideal along and that is universal with this property. IsAmple means that for each point and open , some positive power has a global section with nonvanishing open containing , inside , and affine. A Surface is an integral scheme smooth of relative dimension 2 over with a closed immersion into some complex projective space over . Configuration S r is the set of -tuples of complex points with distinct images, with the Zariski topology induced from the product.
Formalization Note The statement is verbatim from OpenAI's Lean development, with Definitions files of this development imported in place of the upstream modules; these are supporting code for the statement.
import Mathlib import Definitions.Def_MaximalSeshadriConstants import Definitions.Def_SeshadriPrelim6 namespace OAI section namespace MaximalSeshadri.Geometry noncomputable section open AlgebraicGeometry CategoryTheory TopologicalSpace open MaximalSeshadri.Frames MaximalSeshadri.ProjectiveBertini MaximalSeshadri.AlgebraicJets
theorem Surface.exceptional_twist_sections_bounds (S T : Surface)
(L : LineBundle S.scheme) (hL : L.IsAmple)
(A : LineBundle T.scheme) (hA : A.IsAmple)
{r : ℕ} (p : Configuration S r) (f : T.scheme ⟶ S.scheme)
(hf : f ≫ S.structureMap = T.structureMap)
(hbl : IsBlowup (centreIdeal S r p) f)
(J : LineBundle T.scheme) (ι : J.sheaf ⟶ O T.scheme)
(hJ : PresentsPullbackIdeal (centreIdeal S r p) f J ι)
(M : LineBundle S.scheme) (n : ℕ) :
cohomologyDimension T.structureMap ((J.pow n).tensor (M.pullback f)).sheaf 0 ≤
cohomologyDimension S.structureMap M.sheaf 0 ∧
2*cohomologyDimension S.structureMap M.sheaf 0 ≤
2*cohomologyDimension T.structureMap ((J.pow n).tensor (M.pullback f)).sheaf 0 + r*n*(n+1) := by
sorry
end
end MaximalSeshadri.Geometry
end
end OAI