Shor's conjecture on the peak of normalized tree coefficients

At least 4 years old · documented by

Let TT be a tree with n≥3n\geq 3 vertices. Let dk(T)d_k(T) denote the normalized coefficients of the distance characteristic polynomial, defined from the coefficients δk(T)\delta_k(T) by

dk(T)=∣δk(T)∣/2n−k−2.d_k(T)=|\delta_k(T)|/2^{n-k-2}.

A sequence is unimodal if it is nondecreasing up to some index and nonincreasing thereafter. Shor's conjecture. The normalized coefficients d0(T),…,dn−2(T)d_0(T),\dots,d_{n-2}(T) are unimodal, with their peak between ⌊n/2⌋\left\lfloor n/2\right\rfloor and ⌈(1−1/5)n⌉\left\lceil (1-1/\sqrt{5})n\right\rceil.

This is a revised version attributed by Collins to Peter Shor after the Graham–Lovász peak-location claim was disproved. The survey does not provide evidence that this revised conjecture has been resolved.

References

Primary source

Leslie Hogben and Carolyn Reinhart, “Spectra of variants of distance matrices of graphs and digraphs: a survey”, arXiv:2103.00647 (2021).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.