English

Tropical Weierstrass points and Weierstrass weights

Algebraic Geometry 2026-03-27 v3 Combinatorics Number Theory

Abstract

In this paper, we study tropical Weierstrass points. These are the analogues for tropical curves of ramification points of line bundles on algebraic curves. For a divisor on a tropical curve, we associate intrinsic weights to the connected components of the locus of tropical Weierstrass points. These are obtained by analyzing the slopes of rational functions in the complete linear series of the divisor. We prove that for a divisor DD of degree dd and rank rr on a genus gg tropical curve, the sum of weights is equal to dr+rgd - r + rg. We establish analogous statements for tropical linear series. In the case DD comes from the tropicalization of a divisor, these weights control the number of Weierstrass points that are tropicalized to each component. Our results provide answers to open questions originating from the work of Baker on specialization of divisors from curves to graphs. We conclude with multiple examples that illustrate interesting features appearing in the study of tropical Weierstrass points, and raise several open questions.

Keywords

Cite

@article{arxiv.2303.07729,
  title  = {Tropical Weierstrass points and Weierstrass weights},
  author = {Omid Amini and Lucas Gierczak and Harry Richman},
  journal= {arXiv preprint arXiv:2303.07729},
  year   = {2026}
}

Comments

54 pages, 17 figures; final version

R2 v1 2026-06-28T09:15:51.629Z