English

Semialgebric rank-one convex hulls: 2x2 triangular matrices and beyond

Metric Geometry 2025-09-10 v1 Algebraic Geometry Analysis of PDEs

Abstract

We prove that the rank-one convex hull of finitely many 2×22\times 2 triangular matrices is a semialgebraic set, defined by linear and quadratic polynomials. We present explicit constructions for five-point configurations and offer evidence suggesting that a similar characterization does not hold in the more general setting of directional convexity.

Keywords

Cite

@article{arxiv.2509.07541,
  title  = {Semialgebric rank-one convex hulls: 2x2 triangular matrices and beyond},
  author = {Chiara Meroni and Bogdan Raita},
  journal= {arXiv preprint arXiv:2509.07541},
  year   = {2025}
}

Comments

18 pages, comments are welcome!

R2 v1 2026-07-01T05:28:03.702Z