Li–Peng square-root booksize conjecture for Nosal graphs
Let be an -edge graph with spectral radius . Such a graph is called Nosal, and let denote the maximum number of triangles sharing a common edge in .
Li–Peng conjecture. For every -edge Nosal graph ,
Nikiforov had previously shown the weaker bound . The conjecture was confirmed by Li, Liu and Zhang, who proved and showed that the order is best possible.
References
Primary source
Xinghui Zhao, Lihua You, Jing Zeng and Xiaoxue Zhang, “Two problems on booksize and triangular edges in Nosal graphs”, arXiv:2607.15071 (2026).
Additional references
3 papers in this index state this conjecture (2025–2026). The statement above is taken from the most recent of them; the others are arXiv:2601.10163, arXiv:2508.14366.
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