{ "id": "math/0602568", "version": "v1", "published": "2006-02-25T05:39:46.000Z", "updated": "2006-02-25T05:39:46.000Z", "title": "Long zero-free sequences in finite cyclic groups", "authors": [ "Svetoslav Savchev", "Fang Chen" ], "comment": "13 pages", "categories": [ "math.CO", "math.NT" ], "abstract": "A sequence in an additively written abelian group is called zero-free if each of its nonempty subsequences has sum different from the zero element of the group. The article determines the structure of the zero-free sequences with lengths greater than $n/2$ in the additive group $\\Zn/$ of integers modulo $n$. The main result states that for each zero-free sequence $(a_i)_{i=1}^\\ell$ of length $\\ell>n/2$ in $\\Zn/$ there is an integer $g$ coprime to $n$ such that if $\\bar{ga_i}$ denotes the least positive integer in the congruence class $ga_i$ (modulo $n$), then $\\Sigma_{i=1}^\\ell\\bar{ga_i}