The Real Vanishing Ideals of Nuclear p-Norm Balls
Algebraic Geometry
2025-10-29 v1
Abstract
We study the algebraic and geometric structure related to tensor nuclear norms. We show that the unit ball of the nuclear norm is the convex hull of an irreducible real variety and give an explicit description of its real vanishing ideal. As a consequence, we obtain a simple criterion to decide when a primary ideal is prime, and we use it to prove that the ideal of the nuclear 2-norm is real reduced and prime.
Cite
@article{arxiv.2510.24661,
title = {The Real Vanishing Ideals of Nuclear p-Norm Balls},
author = {Ghislain Fourier and Yuhuai Zhou},
journal= {arXiv preprint arXiv:2510.24661},
year = {2025}
}