{ "id": "0808.2234", "version": "v2", "published": "2008-08-16T03:27:11.000Z", "updated": "2009-05-13T23:10:28.000Z", "title": "Sum of squares of degrees in a graph", "authors": [ "Bernardo M. Ábrego", "Silvia Fernández-Merchant", "Michael G. Neubauer", "William Watkins" ], "comment": "40 pages, 11 figures. Updated introduction, a minor issue on the definition of Quasi-complete graphs was fixed, and a couple of references were added", "journal": "J. Inequal. Pure Appl. Math. 10 (2009), no. 3, Article 64, 34 pp", "categories": [ "math.CO" ], "abstract": "Let $\\G(v,e)$ be the set of all simple graphs with $v$ vertices and $e$ edges and let $P_2(G)=\\sum d_i^2$ denote the sum of the squares of the degrees, $d_1, >..., d_v$, of the vertices of $G$. It is known that the maximum value of $P_2(G)$ for $G \\in \\G(v,e)$ occurs at one or both of two special graphs in $\\G(v,e)$--the \\qs graph or the \\qc graph. For each pair $(v,e)$, we determine which of these two graphs has the larger value of $P_2(G)$. We also determine all pairs $(v,e)$ for which the values of $P_2(G)$ are the same for the \\qs and the \\qc graph. In addition to the \\qs and \\qc graphs, we find all other graphs in $\\G(v,e)$ for which the maximum value of $P_2(G)$ is attained. Density questions posed by previous authors are examined.", "revisions": [ { "version": "v2", "updated": "2009-05-13T23:10:28.000Z" } ], "analyses": { "subjects": [ "05C07", "05C35" ], "keywords": [ "maximum value", "simple graphs", "special graphs", "larger value", "density questions" ], "tags": [ "journal article" ], "note": { "typesetting": "TeX", "pages": 40, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2008arXiv0808.2234A" } } }