Normality, factoriality and strong $F$-regularity of Lovász-Saks-Schrijver rings

Fuente: arXiv
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Main Author: Tolosa-Villarreal, Eliana
Format: Preprint
Published: 2024
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author Tolosa-Villarreal, Eliana
author_facet Tolosa-Villarreal, Eliana
contents Every simple finite graph $G$ has an associated Lovász-Saks-Schrijver ring $R_G(d)$ that is related to the $d$-dimensional orthogonal representations of $G$. The study of $R_G(d)$ lies at the intersection between algebraic geometry, commutative algebra and combinatorics. We find a link between algebraic properties such as normality, factoriality and strong $F$-regularity of $R_G(d)$ and combinatorial invariants of the graph $G$. In particular we prove that if $d \geq \text{pmd}(G)+k(G)$ then $R_G(d)$ is $F$-regular in finite characteristic and rational singularity in characteristic $0$ and furthermore if $d \geq \text{pmd}(G)+k(G)+1$ then $R_G(d)$ is UFD. Here $\text{pmd}(G)$ is the positive matching decomposition number of $G$ and $k(G)$ is its degeneracy number.
format Preprint
id arxiv_https___arxiv_org_abs_2405_20480
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Normality, factoriality and strong $F$-regularity of Lovász-Saks-Schrijver rings
Tolosa-Villarreal, Eliana
Commutative Algebra
Combinatorics
Every simple finite graph $G$ has an associated Lovász-Saks-Schrijver ring $R_G(d)$ that is related to the $d$-dimensional orthogonal representations of $G$. The study of $R_G(d)$ lies at the intersection between algebraic geometry, commutative algebra and combinatorics. We find a link between algebraic properties such as normality, factoriality and strong $F$-regularity of $R_G(d)$ and combinatorial invariants of the graph $G$. In particular we prove that if $d \geq \text{pmd}(G)+k(G)$ then $R_G(d)$ is $F$-regular in finite characteristic and rational singularity in characteristic $0$ and furthermore if $d \geq \text{pmd}(G)+k(G)+1$ then $R_G(d)$ is UFD. Here $\text{pmd}(G)$ is the positive matching decomposition number of $G$ and $k(G)$ is its degeneracy number.
title Normality, factoriality and strong $F$-regularity of Lovász-Saks-Schrijver rings
topic Commutative Algebra
Combinatorics
url https://arxiv.org/abs/2405.20480