A Tropical Viewpoint on the Nagata--Biran--Szemberg Conjecture
Abstract
We give a tropical perspective on the recent arguments announced by OpenAI for Nagata's conjecture and the Nagata--Biran--Szemberg conjecture. By degenerating to both the normal cone and a semistable model whose dual graph is a cycle, we replace sections on a surface by Laurent polynomials in two variables. In place of theta functions, tropical methods bound the exponents of these Laurent polynomials, and a lift of the tropical Abel--Jacobi class of the normal bundle controls the shape of the resulting exponent diagram. Combining these support bounds with interpolation on a torus proves the Nagata--Biran--Szemberg conjecture with its predicted threshold whenever the corresponding linear series contains an integral curve whose only singularity is an ordinary node that is not a basepoint.
Related
- Nagata's conjecture on a polynomial automorphism in positive characteristic
- On OpenAI's proof of the Nagata conjecture
- Counterexamples to the Jacobian Conjecture from the viewpoint of lineability
- Discriminants of Hermitian forms, maximal degenerations and Kontsevich's tropical approach to the Hodge conjecture
- Tropical friezes and cluster-additive functions via Fock-Goncharov duality and a conjecture of Ringel
BibTeX
@misc{bruce2026tropical,
title = {{A Tropical Viewpoint on the Nagata--Biran--Szemberg Conjecture}},
author = {Juliette Bruce},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.41931},
eprint = {2610.41931},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.41931},
}
RIS
TY - UNPB
TI - A Tropical Viewpoint on the Nagata--Biran--Szemberg Conjecture
AU - Juliette Bruce
PY - 2026
DA - 2026/10/30
PB - arXiv
DO - 10.48550/arxiv.2610.41931
UR - https://arxiv.org/abs/2610.41931
AB - We give a tropical perspective on the recent arguments announced by OpenAI for Nagata's conjecture and the Nagata--Biran--Szemberg conjecture. By degenerating to both the normal cone and a semistable model whose dual graph is a cycle, we replace sections on a surface by Laurent polynomials in two variables. In place of theta functions, tropical methods bound the exponents of these Laurent polynomials, and a lift of the tropical Abel--Jacobi class of the normal bundle controls the shape of the resulting exponent diagram. Combining these support bounds with interpolation on a torus proves the Nagata--Biran--Szemberg conjecture with its predicted threshold whenever the corresponding linear series contains an integral curve whose only singularity is an ordinary node that is not a basepoint.
ER -