3 papers
math.CO2024
Combined voltage assignments, factored lifts, and their spectra
C. Dalfó, M. A. Fiol, S. Pavlíková +1
We consider lifting eigenvalues and eigenvectors of graphs to their {\em factored lifts}, derived by means of a {\em combined voltage assignment} in a group. The latter extends the…
math.CO2024
Some inner metric parameters of a digraph: Iterated line digraphs and integer sequences
N. H. Bong, C. Dalfó, M. A. Fiol +1
In this paper, we first give a new result characterizing the strongly connected digraphs with a diameter equal to that of their line digraphs. Then, we introduce the concepts of th…
math.CO2024
A note on an infinite family of graphs with all different integral Laplacian eigenvalues
C. Dalfó, M. A. Fiol
In this note, we give an infinite family of optimal graphs called . They are optimal in the sense that they have the maximum possible number of vertices for given a diame…