{ "id": "1908.05072", "version": "v1", "published": "2019-08-14T11:14:49.000Z", "updated": "2019-08-14T11:14:49.000Z", "title": "Light edges in 1-planar graphs of minimum degree 3", "authors": [ "Bei Niu", "Xin Zhang" ], "comment": "This paper was submitted to Discrete Mathematics on Dec.4, 2018, and will be published there", "categories": [ "math.CO", "cs.DM" ], "abstract": "A graph is 1-planar if it can be drawn in the plane so that each edge is crossed by at most one another edge. In this work we prove that each 1-planar graph of minimum degree at least $3$ contains an edge with degrees of its endvertices of type $(3,\\leq23)$ or $(4,\\leq11)$ or $(5,\\leq9)$ or $(6,\\leq8)$ or $(7,7)$. Moreover, the upper bounds $9,8$ and $7$ here are sharp and the upper bounds $23$ and $11$ are very close to the possible sharp ones, which may be 20 and 10, respectively. This generalizes a result of Fabrici and Madaras [Discrete Math., 307 (2007) 854--865] which says that each 3-connected 1-planar graph contains a light edge, and improves a result of Hud\\'ak and \\v{S}ugerek [Discuss. Math. Graph Theory, 32(3) (2012) 545--556], which states that each 1-planar graph of minimum degree at least $4$ contains an edge with degrees of its endvertices of type $(4,\\leq 13)$ or $(5,\\leq 9)$ or $(6,\\leq 8)$ or $(7, 7)$.", "revisions": [ { "version": "v1", "updated": "2019-08-14T11:14:49.000Z" } ], "analyses": { "keywords": [ "minimum degree", "light edge", "upper bounds", "endvertices", "graph theory" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }