9 citations · 16 across the 23 of their papers we have counts for
Showing 2023Show all
3 papers · 1 filter
math.CO2023
Cospectrality results for signed graphs with two eigenvalues unequal to
Willem H. Haemers, Hatice Topcu
Recently the collection of all signed graphs for which the adjacency matrix has all but at most two eigenvalues equal to has been determined. Here we investigate $…
math.CO2023
Cospectral mates for generalized Johnson and Grassmann graphs
Aida Abiad, Jozefien D'haeseleer, Willem H. Haemers +1
We provide three infinite families of graphs in the Johnson and Grassmann schemes that are not uniquely determined by their spectrum. We do so by constructing graphs that are cospe…
math.CO2023
The signed graphs with two eigenvalues unequal to
Willem Haemers, Hatice Topcu
We complete the determination of the signed graphs for which the adjacency matrix has all but at most two eigenvalues equal to . The unsigned graphs and the disconnected, th…