Extremality of tautological classes of matroids in nef cones

Fuente: arXiv
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Main Author: Stastny, Colin
Format: Preprint
Published: 2026
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author Stastny, Colin
author_facet Stastny, Colin
contents We study the extremality properties of rays generated by tautological Chern classes of matroids in the polyhedral nef cones of the permutohedral variety. Our main result provides necessary and sufficient conditions a matroid has to meet for its tautological Chern classes to generate extremal rays. Our approach yields a new and large family of extremal rays that interpolates between two previously known classes coming from rank functions and Bergman classes of matroids. We further discuss how this theorem extends to the stellahedral variety through augmented tautological Chern classes.
format Preprint
id arxiv_https___arxiv_org_abs_2606_01278
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Extremality of tautological classes of matroids in nef cones
Stastny, Colin
Algebraic Geometry
Combinatorics
14C15, 14M25, 52B40, 14C17
We study the extremality properties of rays generated by tautological Chern classes of matroids in the polyhedral nef cones of the permutohedral variety. Our main result provides necessary and sufficient conditions a matroid has to meet for its tautological Chern classes to generate extremal rays. Our approach yields a new and large family of extremal rays that interpolates between two previously known classes coming from rank functions and Bergman classes of matroids. We further discuss how this theorem extends to the stellahedral variety through augmented tautological Chern classes.
title Extremality of tautological classes of matroids in nef cones
topic Algebraic Geometry
Combinatorics
14C15, 14M25, 52B40, 14C17
url https://arxiv.org/abs/2606.01278