English

Birational automorphisms of a three-dimensional double quadric with an elementary singularity

Algebraic Geometry 2015-06-26 v1

Abstract

It is proved that the group of birational automorphisms of a three-dimensional double quadric with a singular point arising from a double point on the branch divisor is a semidirect product of the free group generated by birational involutions of a special form and the group of regular automorphisms. The proof is based on the method of `untwisting' maximal singularities of linear systems.

Keywords

Cite

@article{arxiv.math/9808073,
  title  = {Birational automorphisms of a three-dimensional double quadric with an elementary singularity},
  author = {Mikhail Grinenko},
  journal= {arXiv preprint arXiv:math/9808073},
  year   = {2015}
}

Comments

18 pages

R2 v1 2026-07-22T17:59:38.530Z