Fajtlowicz's conjecture on average neighbour degree and distance spectra
Let be a finite simple connected graph of order . For each vertex , let be its degree and its open neighbourhood, and define
Let be the distance matrix of , and write for its smallest eigenvalue. Fajtlowicz's conjecture. If has order at least three and girth at least five, then
This is a Graffiti conjecture attributed to Fajtlowicz's 1998 Written on the Wall report and recorded by Aouchiche and Hansen. Its resolution is not established by the supplied text.
References
Primary source
Samuil Petkov, “Counterexamples, Spectral Obstructions, and Deletion Stability for WOW-284”, arXiv:2607.27452 (2026).
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