3 research outputs found
Kissing numbers of regular graphs
We prove a sharp upper bound on the number of shortest cycles contained
inside any connected graph in terms of its number of vertices, girth, and maximal degree.
Equality holds only for Moore graphs, which gives a new characterization of these graphs.
In the case of regular graphs, our result improves an inequality of Teo and Koh. We also
show that a subsequence of the Ramanujan graphs of Lubotzky–Phillips–Sarnak have
super-linear kissing numbers