On the regularity index of the minimum distance function in projective nested Cartesian codes

Fuente: arXiv
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Main Authors: Carvalho, Cicero, Pinto, Maria Vaz, Villarreal, Rafael H.
Format: Preprint
Published: 2026
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author Carvalho, Cicero
Pinto, Maria Vaz
Villarreal, Rafael H.
author_facet Carvalho, Cicero
Pinto, Maria Vaz
Villarreal, Rafael H.
contents Let $X$ be a projective nested product of fields and let $δ_X(d)$ be the minimum distance in degree $d\geq 1$ of the projective nested Cartesian code $C_X(d)$. The regularity index ${\rm reg}(δ_X)$ of the minimum distance function $δ_X$ is the minimum integer $d_0\geq 0$ such that $δ_X(d)=1$ for $d\geq d_0$. We give a formula for ${\rm reg}(δ_X)$ by determining an indicator function of least degree for each point of $X$ and using the fact that ${\rm reg}(δ_X)$ is the ${\rm v}$-number of the vanishing ideal $I_X$ of $X$. Then we give an arithmetical criterion that characterizes when $X$ is Cayley--Bacharach.
format Preprint
id arxiv_https___arxiv_org_abs_2604_20729
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On the regularity index of the minimum distance function in projective nested Cartesian codes
Carvalho, Cicero
Pinto, Maria Vaz
Villarreal, Rafael H.
Commutative Algebra
Information Theory
Algebraic Geometry
13P25, 14G50, 94B27
Let $X$ be a projective nested product of fields and let $δ_X(d)$ be the minimum distance in degree $d\geq 1$ of the projective nested Cartesian code $C_X(d)$. The regularity index ${\rm reg}(δ_X)$ of the minimum distance function $δ_X$ is the minimum integer $d_0\geq 0$ such that $δ_X(d)=1$ for $d\geq d_0$. We give a formula for ${\rm reg}(δ_X)$ by determining an indicator function of least degree for each point of $X$ and using the fact that ${\rm reg}(δ_X)$ is the ${\rm v}$-number of the vanishing ideal $I_X$ of $X$. Then we give an arithmetical criterion that characterizes when $X$ is Cayley--Bacharach.
title On the regularity index of the minimum distance function in projective nested Cartesian codes
topic Commutative Algebra
Information Theory
Algebraic Geometry
13P25, 14G50, 94B27
url https://arxiv.org/abs/2604.20729