On zero-sum problems over metacyclic groups $C_n \rtimes_s C_2$

Fuente: arXiv
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Main Authors: Oh, Jun Seok, Ribas, Sávio, Zhao, Kevin, Zhong, Qinghai
Format: Preprint
Published: 2025
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author Oh, Jun Seok
Ribas, Sávio
Zhao, Kevin
Zhong, Qinghai
author_facet Oh, Jun Seok
Ribas, Sávio
Zhao, Kevin
Zhong, Qinghai
contents Let $G$ be a finite group. A finite collection of elements from $G$, where the order is disregarded and repetitions are allowed, is said to be a product-one sequence if its elements can be ordered such that their product in $G$ equals the identity element of $G$. Then, the Gao's constant $\mathsf E (G)$ of $G$ is the smallest integer $\ell$ such that every sequence of length at least $\ell$ has a product-one subsequence of length $|G|$. For a positive integer $n$, we denote by $C_n$ a cyclic group of order $n$. Let $G = C_n \rtimes_s C_2$ with $s^2\equiv 1\pmod n$ be a metacyclic group. The direct and inverse problems of $\mathsf E (G)$ were settled recently, except for the case that $G=C_{3n_2}\rtimes_s C_2$ with $n_2\neq 1$, $\gcd(n_2,6)=1$, $s\equiv -1 \pmod 3$, and $s\equiv 1\pmod {n_2}$. In this paper, we complete the remaining case and hence for all metacyclic groups of the form $G=C_n \rtimes C_2$, the Gao's constant and the associated inverse problem are now fully settled (see Theorem 1.2).
format Preprint
id arxiv_https___arxiv_org_abs_2511_18246
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On zero-sum problems over metacyclic groups $C_n \rtimes_s C_2$
Oh, Jun Seok
Ribas, Sávio
Zhao, Kevin
Zhong, Qinghai
Combinatorics
Number Theory
11B75, 11P70, 20D60
Let $G$ be a finite group. A finite collection of elements from $G$, where the order is disregarded and repetitions are allowed, is said to be a product-one sequence if its elements can be ordered such that their product in $G$ equals the identity element of $G$. Then, the Gao's constant $\mathsf E (G)$ of $G$ is the smallest integer $\ell$ such that every sequence of length at least $\ell$ has a product-one subsequence of length $|G|$. For a positive integer $n$, we denote by $C_n$ a cyclic group of order $n$. Let $G = C_n \rtimes_s C_2$ with $s^2\equiv 1\pmod n$ be a metacyclic group. The direct and inverse problems of $\mathsf E (G)$ were settled recently, except for the case that $G=C_{3n_2}\rtimes_s C_2$ with $n_2\neq 1$, $\gcd(n_2,6)=1$, $s\equiv -1 \pmod 3$, and $s\equiv 1\pmod {n_2}$. In this paper, we complete the remaining case and hence for all metacyclic groups of the form $G=C_n \rtimes C_2$, the Gao's constant and the associated inverse problem are now fully settled (see Theorem 1.2).
title On zero-sum problems over metacyclic groups $C_n \rtimes_s C_2$
topic Combinatorics
Number Theory
11B75, 11P70, 20D60
url https://arxiv.org/abs/2511.18246