{ "id": "2105.02297", "version": "v1", "published": "2021-05-05T19:38:21.000Z", "updated": "2021-05-05T19:38:21.000Z", "title": "Remarks on the spectral radius of $K_{r+1}$-saturated graphs", "authors": [ "V. Nikiforov" ], "comment": "6 pages", "categories": [ "math.CO" ], "abstract": "Write $\\rho\\left( G\\right) $ for the spectral radius of a graph $G$ and $S_{n,r}$ for the join $K_{r}\\vee\\overline{K}_{n-r}.$ Let $n>r\\geq2$ and $G$ be a $K_{r+1}$-saturated graph of order $n.$ Recently Kim, Kim, Kostochka, and O determined exactly the minimum value of $\\rho\\left( G\\right) $ for $r=2$, and found an asymptotically tight bound on $\\rho\\left( G\\right) $ for $r\\geq3.$ They also conjectured that \\[ \\rho\\left( G\\right) >\\rho\\left( S_{n,r-1}\\right) , \\] unless $G=S_{n,r-1}.$ In this note their conjecture is proved.", "revisions": [ { "version": "v1", "updated": "2021-05-05T19:38:21.000Z" } ], "analyses": { "subjects": [ "05C50" ], "keywords": [ "spectral radius", "saturated graph", "minimum value", "asymptotically tight bound", "conjecture" ], "note": { "typesetting": "TeX", "pages": 6, "language": "en", "license": "arXiv", "status": "editable" } } }