{ "id": "1908.05650", "version": "v1", "published": "2019-08-15T17:47:21.000Z", "updated": "2019-08-15T17:47:21.000Z", "title": "The maximum number of points in the cross-polytope that form a packing set of a scaled cross-polytope", "authors": [ "Ji Hoon Chun" ], "categories": [ "math.MG" ], "abstract": "The problem of finding the largest number of points in the unit cross-polytope such that the $l_{1}$-distance between any two distinct points is at least $2r$ is investigated for $r\\in\\left(1-\\frac{1}{n},1\\right]$ in dimensions $\\geq2$ and for $r\\in\\left(\\frac{1}{2},1\\right]$ in dimension $3$. For the $n$-dimensional cross-polytope, $2n$ points can be placed when $r\\in\\left(1-\\frac{1}{n},1\\right]$. For the three-dimensional cross-polytope, $10$ and $12$ points can be placed if and only if $r\\in\\left(\\frac{3}{5},\\frac{2}{3}\\right]$ and $r\\in\\left(\\frac{4}{7},\\frac{3}{5}\\right]$ respectively, and no more than $14$ points can be placed when $r\\in\\left(\\frac{1}{2},\\frac{4}{7}\\right]$. Also, constructive arrangements of points that attain the upper bounds of $2n$, $10$, and $12$ are provided, as well as $13$ points for dimension $3$ when $r\\in\\left(\\frac{1}{2},\\frac{6}{11}\\right]$.", "revisions": [ { "version": "v1", "updated": "2019-08-15T17:47:21.000Z" } ], "analyses": { "keywords": [ "maximum number", "packing set", "scaled cross-polytope", "upper bounds", "three-dimensional cross-polytope" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }