Stellahedral geometry of matroids

C Eur, J Huh, M Larson - Forum of Mathematics, Pi, 2023 - cambridge.org
We use the geometry of the stellahedral toric variety to study matroids. We identify the
valuative group of matroids with the cohomology ring of the stellahedral toric variety and …

Valuative invariants for large classes of matroids

L Ferroni, B Schröter - Journal of the London Mathematical …, 2024 - Wiley Online Library
We study an operation in matroid theory that allows one to transition a given matroid into
another with more bases via relaxing a stressed subset. This framework provides a new …

Tautological classes of matroids

A Berget, C Eur, H Spink, D Tseng - Inventiones mathematicae, 2023 - Springer
We introduce certain torus-equivariant classes on permutohedral varieties which we call
“tautological classes of matroids” as a new geometric framework for studying matroids …

A semi-small decomposition of the Chow ring of a matroid

T Braden, J Huh, JP Matherne, N Proudfoot… - Advances in …, 2022 - Elsevier
We give a semi-small orthogonal decomposition of the Chow ring of a matroid M. The
decomposition is used to give simple proofs of Poincaré duality, the hard Lefschetz theorem …

[PDF][PDF] Combinatorics and Hodge theory

J Huh - Proceedings of the international congress of …, 2022 - ncatlab.org
I will tell two interrelated stories illustrating fruitful interactions between combinatorics and
Hodge theory. The first is that of Lorentzian polynomials, based on my joint work with Petter …

Intersection theory of polymatroids

C Eur, M Larson - International Mathematics Research Notices, 2024 - academic.oup.com
Polymatroids are combinatorial abstractions of subspace arrangements in the same way that
matroids are combinatorial abstractions of hyperplane arrangements. By introducing …

[HTML][HTML] Hilbert–Poincaré series of matroid Chow rings and intersection cohomology

L Ferroni, JP Matherne, M Stevens, L Vecchi - Advances in Mathematics, 2024 - Elsevier
We study the Hilbert series of four objects arising in the Chow-theoretic and Kazhdan–
Lusztig framework of matroids. These are, respectively, the Hilbert series of the Chow ring …

Signed permutohedra, delta‐matroids, and beyond

C Eur, A Fink, M Larson, H Spink - Proceedings of the London …, 2024 - Wiley Online Library
We establish a connection between the algebraic geometry of the type BB permutohedral
toric variety and the combinatorics of delta‐matroids. Using this connection, we compute the …

Stressed hyperplanes and Kazhdan–Lusztig gamma-positivity for matroids

L Ferroni, GD Nasr, L Vecchi - … Mathematics Research Notices, 2023 - academic.oup.com
In this article, we make several contributions of independent interest. First, we introduce the
notion of stressed hyperplane of a matroid, essentially a type of cyclic flat that permits to …

K-rings of wonderful varieties and matroids

M Larson, S Li, S Payne, N Proudfoot - Advances in Mathematics, 2024 - Elsevier
We study the K-ring of the wonderful variety of a hyperplane arrangement and give a
combinatorial presentation that depends only on the underlying matroid. We use this …