Computational Aspects of the Short Resolution

Fuente: arXiv
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Main Authors: García-Marco, Ignacio, Gimenez, Philippe, González-Sánchez, Mario
Format: Preprint
Published: 2025
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author García-Marco, Ignacio
Gimenez, Philippe
González-Sánchez, Mario
author_facet García-Marco, Ignacio
Gimenez, Philippe
González-Sánchez, Mario
contents Let $R:= \Bbbk[x_1,\ldots,x_{n}]$ be a polynomial ring over a field $\Bbbk$, $I \subset R$ be a homogeneous ideal with respect to a weight vector $ω= (ω_1,\ldots,ω_n) \in (\mathbb{Z}^+)^n$, and denote by $d$ the Krull dimension of $R/I$. In this paper we study graded free resolutions of $R/I$ as $A$-module whenever $A :=\Bbbk[x_{n-d+1},\ldots,x_n]$ is a Noether normalization of $R/I$. We exhibit a Schreyer-like method to compute a (non-necessarily minimal) graded free resolution of $R/I$ as $A$-module. When $R/I$ is a $3$-dimensional simplicial toric ring, we describe how to prune the previous resolution to obtain a minimal one. We finally provide an example of a $6$-dimensional simplicial toric ring whose Betti numbers, both as $R$-module and as $A$-module, depend on the characteristic of $\Bbbk$.
format Preprint
id arxiv_https___arxiv_org_abs_2504_12019
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Computational Aspects of the Short Resolution
García-Marco, Ignacio
Gimenez, Philippe
González-Sánchez, Mario
Commutative Algebra
Algebraic Geometry
14Q15, 13D02, 14Q10, 13F65, 20M50
Let $R:= \Bbbk[x_1,\ldots,x_{n}]$ be a polynomial ring over a field $\Bbbk$, $I \subset R$ be a homogeneous ideal with respect to a weight vector $ω= (ω_1,\ldots,ω_n) \in (\mathbb{Z}^+)^n$, and denote by $d$ the Krull dimension of $R/I$. In this paper we study graded free resolutions of $R/I$ as $A$-module whenever $A :=\Bbbk[x_{n-d+1},\ldots,x_n]$ is a Noether normalization of $R/I$. We exhibit a Schreyer-like method to compute a (non-necessarily minimal) graded free resolution of $R/I$ as $A$-module. When $R/I$ is a $3$-dimensional simplicial toric ring, we describe how to prune the previous resolution to obtain a minimal one. We finally provide an example of a $6$-dimensional simplicial toric ring whose Betti numbers, both as $R$-module and as $A$-module, depend on the characteristic of $\Bbbk$.
title Computational Aspects of the Short Resolution
topic Commutative Algebra
Algebraic Geometry
14Q15, 13D02, 14Q10, 13F65, 20M50
url https://arxiv.org/abs/2504.12019