English

A cospectral construction for the generalized distance matrix

Combinatorics 2024-12-10 v1

Abstract

The generalized distance matrix of a graph is a matrix in which the (i,j)(i,j)th entry is a function, ff, of the distance between vertex ii and vertex jj. Depending on the choice of ff, this family of matrices includes both the adjacency matrix and the traditional distance matrix. We present a cospectral construction for the generalized distance matrix akin to Godsil-McKay Switching. We also investigate a special case of the generalized distance matrix: the exponential distance matrix, which is a matrix where every entry is a value qq raised to the power of the distance between the vertices. We give an upper bound on the values of qq needed to show a pair of graphs is cospectral for all values of qq corresponding to the diameter of the graphs. We also give cospectral constructions unique to value q=1/2q=1/2.

Cite

@article{arxiv.2412.05389,
  title  = {A cospectral construction for the generalized distance matrix},
  author = {Ori Friesen and Cecily Kolko and Nick Layman and Kate Lorenzen and Sarah Zaske and Amy Zeigler},
  journal= {arXiv preprint arXiv:2412.05389},
  year   = {2024}
}
R2 v1 2026-06-28T20:26:10.919Z