{ "id": "1202.0681", "version": "v2", "published": "2012-02-03T12:39:14.000Z", "updated": "2012-08-10T14:34:39.000Z", "title": "On maximum matchings in almost regular graphs", "authors": [ "Petros A. Petrosyan" ], "comment": "5 pages", "categories": [ "math.CO", "cs.DM" ], "abstract": "In 2010, Mkrtchyan, Petrosyan and Vardanyan proved that every graph $G$ with $2\\leq \\delta(G)\\leq \\Delta(G)\\leq 3$ contains a maximum matching whose unsaturated vertices do not have a common neighbor, where $\\Delta(G)$ and $\\delta(G)$ denote the maximum and minimum degrees of vertices in $G$, respectively. In the same paper they suggested the following conjecture: every graph $G$ with $\\Delta(G)-\\delta(G)\\leq 1$ contains a maximum matching whose unsaturated vertices do not have a common neighbor. Recently, Picouleau disproved this conjecture by constructing a bipartite counterexample $G$ with $\\Delta(G)=5$ and $\\delta(G)=4$. In this note we show that the conjecture is false for graphs $G$ with $\\Delta(G)-\\delta(G)=1$ and $\\Delta(G)\\geq 4$, and for $r$-regular graphs when $r\\geq 7$.", "revisions": [ { "version": "v2", "updated": "2012-08-10T14:34:39.000Z" } ], "analyses": { "keywords": [ "regular graphs", "maximum matching", "common neighbor", "unsaturated vertices", "conjecture" ], "note": { "typesetting": "TeX", "pages": 5, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2012arXiv1202.0681P" } } }