Graph transformations and eigenvectors of the Laplacian, signless Laplacian and Adjacency matrices
Abstract
We study graph transformations and their effects on the eigenvectors of three fundamental graph matrices: the adjacency matrix A, the signless Laplacian Q, and the Laplacian L. We extend the Laplacian eigenvector edge and matching principles introduced by Merris to Q and A. We also extend some of the known L graph transformations to Q and A and prove that graphs admitting a common eigenvector x for $A, L$ and Q are such that vertices corresponding to nonzero components of x have same degree. Following our previous work for L, we investigate bivalent graphs for A and Q, that is graphs admitting an eigenvector with all components in {−1, 1}. In particular, for trees, we characterize Q-bivalence and establish that A-bivalence forces all vertex degrees to be odd.
Related
- The Distance Laplacian and Distance Signless Laplacian Spectra of 𝒞-Graphs
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- The signless Laplacian spectral Turán problems for disjoint triangles
- On the Brouwer-type Conjecture for Signless Laplacian Eigenvalues of Graphs
- Proofs of Li, Wang and Guo's conjectures on (signless) Laplacian spectral radius
BibTeX
@misc{caputo2026graph,
title = {{Graph transformations and eigenvectors of the Laplacian, signless Laplacian and Adjacency matrices}},
author = {Jean-Guy Caputo and Leonardo de Lima and Arnaud Knippel},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.09599},
eprint = {2610.09599},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.09599},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Graph transformations and eigenvectors of the Laplacian, signless Laplacian and Adjacency matrices
AU - Jean-Guy Caputo
AU - Leonardo de Lima
AU - Arnaud Knippel
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2610.09599
UR - https://arxiv.org/abs/2610.09599
AB - We study graph transformations and their effects on the eigenvectors of three fundamental graph matrices: the adjacency matrix A, the signless Laplacian Q, and the Laplacian L. We extend the Laplacian eigenvector edge and matching principles introduced by Merris to Q and A. We also extend some of the known L graph transformations to Q and A and prove that graphs admitting a common eigenvector x for $A, L$ and Q are such that vertices corresponding to nonzero components of x have same degree. Following our previous work for L, we investigate bivalent graphs for A and Q, that is graphs admitting an eigenvector with all components in {−1, 1}. In particular, for trees, we characterize Q-bivalence and establish that A-bivalence forces all vertex degrees to be odd.
ER -