From the 1 of 2 linked papers with an AI index.
2 papers
math.CO2026
Graphs with zero as a main eigenvalue of the signless Laplacian
Hangxi Cha, Haiying Shan
An eigenvalue of the signless Laplacian is -main if its eigenspace is not orthogonal to the all-ones vector. We characterize graphs with exactly -main eigen…
math.CO2026
Trees with exactly three main eigenvalues
Hangxi Cha, Haiying Shan
The paper classifies all trees of diameter five that have exactly three main eigenvalues, showing they are either symmetric trees T_r(a) or belong to a parametric family defined by…