{ "id": "1409.6065", "version": "v1", "published": "2014-09-22T01:58:49.000Z", "updated": "2014-09-22T01:58:49.000Z", "title": "Edge-connectivity in regular multigraphs from eigenvalues", "authors": [ "Suil O" ], "comment": "11 pages, 2 figures (in press, Linear Algebra and its Application)", "doi": "10.1016/j.laa.2014.09.015", "categories": [ "math.CO" ], "abstract": "Let $G$ be a $d$-regular multigraph, and let $\\lambda_2(G)$ be the second largest eigenvalue of $G$. In this paper, we prove that if $\\lambda_2(G) < \\frac{d-1+\\sqrt{9d^2-10d+17}}4$, then $G$ is 2-edge-connected. Furthermore, for $t\\ge2$ we show that $G$ is $(t+1)$-edge-connected when $\\lambda_2(G)