The number of triangles is more when they have no common vertex

نویسندگان

چکیده

By the theorem of Mantel (1907) it is known that a graph with n vertices and ⌊n24⌋+1 edges must contain triangle. A Erdős gives strengthening: there are not only one, but at least ⌊n2⌋ triangles. We give further improvement: if no vertex contained by all triangles then n−2 them. There some natural generalizations when (a) complete graphs considered (rather than triangles), (b) has t extra (not one) or (c) supposed s such every triangle contains one were able to prove these generalizations, they posed as conjectures.

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ژورنال

عنوان ژورنال: Discrete Mathematics

سال: 2021

ISSN: ['1872-681X', '0012-365X']

DOI: https://doi.org/10.1016/j.disc.2021.112330