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Arithmetic purity of strong approximation for semi-simple simply connected groups

Research output: Contribution to journalArticleResearchpeer review

Authors

  • Yang Cao
  • Zhizhong Huang

External Research Organisations

  • University of Science and Technology of China
  • Max Planck Institute for Mathematics

Details

Original languageEnglish
Pages (from-to)2628-2649
Number of pages22
JournalCompositio Mathematica
Volume156
Issue number12
Publication statusPublished - 1 Feb 2021
Externally publishedYes

Abstract

In this article we establish the arithmetic purity of strong approximation for certain semisimple simply connected linear algebraic groups and their homogeneous spaces over a number field k. For instance, for any such group G and for any open subset U of G with codim(G \ U, G) ≥ 2, we prove that (i) if G is k-simple and k-isotropic, then U satisfies strong approximation off any finite number of places; and (ii) if G is the spin group of a non-degenerate quadratic form which is not compact over archimedean places, then U satisfies strong approximation off all archimedean places. As a consequence, we prove that the same property holds for affine quadratic hypersurfaces. Our approach combines a fibration method with subgroup actions developed for induction on the codimension of G \ U, and an affine linear sieve which allows us to produce integral points with almost-prime polynomial values.

Keywords

    math.NT, math.AG, 14G12, 11G35, 20G35, 11N36

Cite this

Arithmetic purity of strong approximation for semi-simple simply connected groups. / Cao, Yang; Huang, Zhizhong.
In: Compositio Mathematica, Vol. 156, No. 12, 01.02.2021, p. 2628-2649.

Research output: Contribution to journalArticleResearchpeer review

Cao Y, Huang Z. Arithmetic purity of strong approximation for semi-simple simply connected groups. Compositio Mathematica. 2021 Feb 1;156(12):2628-2649. doi: 10.48550/arXiv.1906.06967, 10.1112/S0010437X20007617
Cao, Yang ; Huang, Zhizhong. / Arithmetic purity of strong approximation for semi-simple simply connected groups. In: Compositio Mathematica. 2021 ; Vol. 156, No. 12. pp. 2628-2649.
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