Fajtlowicz's conjecture on average neighbour degree and distance spectra
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.
Sources & referencesView supporting material
Primary source
Samuil Petkov, “Counterexamples, Spectral Obstructions, and Deletion Stability for WOW-284”, arXiv:2607.27452 (2026).
Progress summary
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