English

Embeddings and intersections of adelic groups

Algebraic Geometry 2026-04-21 v2 Commutative Algebra

Abstract

We prove embeddings of adelic groups on an excellent scheme of special type and a flat quasicoherent sheaf on it. For a normal excellent scheme of special type we establish the equality AI(X,F)AJ(X,F)=AI0(X,F)\mathbb{A}_I(X,\mathcal{F})\cap\mathbb{A}_J(X,\mathcal{F})=\mathbb{A}_{I\setminus0}(X,\mathcal{F}) in the case IJ=I0I\cap J=I\setminus0. We show that the limit of restrictions of global sections of a locally free sheaf on a Cohen-Macaulay projective scheme to power thickenings of integral subschemes equals the group of global sections of this sheaf. Using this result, we deduce a theorem on intersections of adelic groups for normal projective surfaces. We also compute cohomology groups of a curtailed adelic complex and, as a consequence, show that on a three-dimensional regular projective variety over a countable field the intersection AI(X,F)AJ(X,F)\mathbb{A}_I(X,\mathcal{F})\cap\mathbb{A}_J(X,\mathcal{F}) equals AIJ(X,F)\mathbb{A}_{I\cap J}(X,\mathcal{F}) for any I,J{0,1,2,3}I,J\subset\{0,1,2,3\} and any locally free sheaf F\mathcal{F} on XX.

Keywords

Cite

@article{arxiv.2510.22408,
  title  = {Embeddings and intersections of adelic groups},
  author = {Dmitry Badulin},
  journal= {arXiv preprint arXiv:2510.22408},
  year   = {2026}
}

Comments

42 pages. v2: Added remarks 1.1.18 and 1.2.8, added a reference, edited abstract, edited introduction, other changes

R2 v1 2026-07-01T07:05:53.372Z