{ "id": "1206.3211", "version": "v1", "published": "2012-06-14T18:57:04.000Z", "updated": "2012-06-14T18:57:04.000Z", "title": "Matchings and Independent Sets of a Fixed Size in Regular Graphs", "authors": [ "Teena Carroll", "David Galvin", "Prasad Tetali" ], "comment": "13 pages. Appeared in Journal of Combinatorial Theory Series A in 2009", "categories": [ "math.CO" ], "abstract": "We use an entropy based method to study two graph maximization problems. We upper bound the number of matchings of fixed size $\\ell$ in a $d$-regular graph on $N$ vertices. For $\\frac{2\\ell}{N}$ bounded away from 0 and 1, the logarithm of the bound we obtain agrees in its leading term with the logarithm of the number of matchings of size $\\ell$ in the graph consisting of $\\frac{N}{2d}$ disjoint copies of the complete bipartite graph $K_{d,d}$. This provides asymptotic evidence for a conjecture of S. Friedland {\\it et al.}. We also obtain an analogous result for independent sets of a fixed size in regular graphs, giving asymptotic evidence for a conjecture of J. Kahn. Our bounds on the number of matchings and independent sets of a fixed size are derived from bounds on the partition function (or generating polynomial) for matchings and independent sets.", "revisions": [ { "version": "v1", "updated": "2012-06-14T18:57:04.000Z" } ], "analyses": { "subjects": [ "05C69", "05C70", "05C35" ], "keywords": [ "independent sets", "regular graph", "fixed size", "asymptotic evidence", "graph maximization problems" ], "note": { "typesetting": "TeX", "pages": 13, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2012arXiv1206.3211C" } } }