English

The set of forms with bounded strength is not closed

Algebraic Geometry 2022-05-02 v2 Commutative Algebra Representation Theory

Abstract

The strength of a homogeneous polynomial (or form) is the smallest length of an additive decomposition expressing it whose summands are reducible forms. Using polynomial functors, we show that the set of forms with bounded strength is not always Zariski-closed. More specifically, if the ground field is algebraically closed, we prove that the set of quartics with strength 3\leq3 is not Zariski-closed for a large number of variables.

Keywords

Cite

@article{arxiv.2012.01237,
  title  = {The set of forms with bounded strength is not closed},
  author = {Edoardo Ballico and Arthur Bik and Alessandro Oneto and Emanuele Ventura},
  journal= {arXiv preprint arXiv:2012.01237},
  year   = {2022}
}

Comments

9 pages, removed condition on characteristic

R2 v1 2026-06-23T20:40:24.737Z