Erdős Problem #905

Every graph with $n$ vertices and $>n^2/4$ edges contains an edge which is in at least $n/6$ triangles.

graph theory

A conjecture of Bollobás and Erdős. This was proved independently by Edwards (unpublished) and Hadziivanov and Nikiforov [KhNi79].

For a more general problem see [80]. A stronger version is asked in [1034].

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This page was last edited 06 October 2025.

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