{ "id": "2003.02511", "version": "v1", "published": "2020-03-05T10:01:19.000Z", "updated": "2020-03-05T10:01:19.000Z", "title": "On zero-sum free sequences contained in random subsets of finite cyclic groups", "authors": [ "Sang June Lee", "Jun Seok Oh" ], "comment": "15 pages", "categories": [ "math.CO", "math.NT" ], "abstract": "Let $C_n$ be a cyclic group of order $n$. A sequence $S$ of length $\\ell$ over $C_n$ is a sequence $S = a_1\\boldsymbol\\cdot a_2\\boldsymbol\\cdot \\ldots\\boldsymbol\\cdot a_{\\ell}$ of $\\ell$ elements in $C_n$, where a repetition of elements is allowed and their order is disregarded. We say that $S$ is a zero-sum sequence if $\\Sigma_{i=1}^{\\ell} a_i = 0$ and that $S$ is a zero-sum free sequence if $S$ contains no zero-sum subsequence. Let $R$ be a random subset of $C_n$ obtained by choosing each element in $C_n$ independently with probability $p$. Let $N^R_{n-1-k}$ be the number of zero-sum free sequences of length $n-1-k$ in $R$. Also, let $N^R_{n-1-k,d}$ be the number of zero-sum free sequences of length $n-1-k$ having $d$ distinct elements in $R$. We obtain the expectation of $N^R_{n-1-k}$ and $N^R_{n-1-k,d}$ for $0\\leq k\\leq \\big\\lfloor \\frac{n}{3} \\big\\rfloor$. We also show a concentration result on $N^R_{n-1-k}$ and $N^R_{n-1-k,d}$ when $k$ is fixed.", "revisions": [ { "version": "v1", "updated": "2020-03-05T10:01:19.000Z" } ], "analyses": { "subjects": [ "11B50", "11B30", "05D40" ], "keywords": [ "zero-sum free sequence", "finite cyclic groups", "random subset", "distinct elements", "zero-sum subsequence" ], "note": { "typesetting": "TeX", "pages": 15, "language": "en", "license": "arXiv", "status": "editable" } } }