Singular matroid realization spaces

Fuente: arXiv
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Autori principali: Corey, Daniel, Luber, Dante
Natura: Preprint
Pubblicazione: 2023
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author Corey, Daniel
Luber, Dante
author_facet Corey, Daniel
Luber, Dante
contents We study smoothness of realization spaces of matroids for small rank and ground set. For $\mathbb{C}$-realizable matroids, when the rank is $3$, we prove that the realization spaces are all smooth when the ground set has $11$ or fewer elements, and there are singular realization spaces for $12$ and greater elements. For rank $4$ and $9$ or fewer elements, we prove that these realization spaces are smooth. As an application, we prove that $\text{Gr}^{\circ}(3,n;\mathbb{C})$ -- the locus of the Grassmannian where all Plücker coordinates are nonzero -- is not schön for $n\geq 12$.
format Preprint
id arxiv_https___arxiv_org_abs_2307_11915
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Singular matroid realization spaces
Corey, Daniel
Luber, Dante
Algebraic Geometry
Combinatorics
14B05 (primary) 05E14, 14T90, 52B40 (secondary)
We study smoothness of realization spaces of matroids for small rank and ground set. For $\mathbb{C}$-realizable matroids, when the rank is $3$, we prove that the realization spaces are all smooth when the ground set has $11$ or fewer elements, and there are singular realization spaces for $12$ and greater elements. For rank $4$ and $9$ or fewer elements, we prove that these realization spaces are smooth. As an application, we prove that $\text{Gr}^{\circ}(3,n;\mathbb{C})$ -- the locus of the Grassmannian where all Plücker coordinates are nonzero -- is not schön for $n\geq 12$.
title Singular matroid realization spaces
topic Algebraic Geometry
Combinatorics
14B05 (primary) 05E14, 14T90, 52B40 (secondary)
url https://arxiv.org/abs/2307.11915