40 citations · 62 across the 15 of their papers we have counts for
15 papers
On the second largest eigenvalue of some Cayley graphs of the Symmetric Group
Johannes Siemons, Alexandre Zalesski
Let and denote the symmetric and alternating group on the set respectively. In this paper we are interested in the second largest eigenvalue …
Singular Graphs with Dihedral Group Action
Ali Sltan Ali AL-Tarimshawy, J. Siemons
Let be a simple undirected graph on a finite vertex set and let be its adjacency matrix. Then is {\it singular} if is singular. The problem of characterising singul…
Unlocking the walk matrix of a graph
Fenjin Liu, Johannes Siemons
Let be a graph with vertex set and adjacency matrix For a subset of let $\e=(x_{1},\,\dots,\,x_{n})^{\tt T}$ be the characteristic vector…
Remarks on singular Cayley graphs and vanishing elements of simple groups
Johannes Siemons, Alexandre Zalesski
Let be a finite graph and let be its adjacency matrix. Then is {\it singular} if is singular. The singularity of graphs is of certain interest in graph theory…
New families of graphs determined by their generalized spectrum
Fenjin Liu, Johannes Siemons, Wei Wang
We construct infinite families of graphs that are determined by their generalized spectrum. This construction is based on new formulae for the determinant of the walk matrix of a g…
Permutation Modules associated to the Hyperoctahedron and Group Actions
Johannes Siemons, Benjamin Summers
We investigate the permutation modules associated to the set of -dimensional faces of the hyperoctahedron in dimension , denoted For any such a module can…