{ "id": "2205.07498", "version": "v1", "published": "2022-05-16T08:14:11.000Z", "updated": "2022-05-16T08:14:11.000Z", "title": "On density of $Z_3$-flow-critical graphs", "authors": [ "Zdeněk Dvořák", "Bojan Mohar" ], "comment": "22 pages, no figures", "categories": [ "math.CO" ], "abstract": "For an abelian group $\\Gamma$, a graph $G$ is said to be $\\Gamma$-flow-critical if $G$ does not admit a nowhere-zero $\\Gamma$-flow, but for each edge $e\\in E(G)$, the contraction $G/e$ has a nowhere-zero $\\Gamma$-flow. A bound on the density of $Z_3$-flow-critical graphs drawn on a fixed surface is obtained, generalizing the bound on the density of 4-critical graphs by Kostochka and Yancey.", "revisions": [ { "version": "v1", "updated": "2022-05-16T08:14:11.000Z" } ], "analyses": { "subjects": [ "05C21" ], "keywords": [ "abelian group", "nowhere-zero", "flow-critical graphs drawn", "contraction" ], "note": { "typesetting": "TeX", "pages": 22, "language": "en", "license": "arXiv", "status": "editable" } } }