On the diameter of the commuting graph of the full matrix ring over the real numbers

Jose Maria Grau, Antonio Oller-Marcen, Carmen Tasis

In a recent paper C. Miguel proved that the diameter of the commuting graph of the matrix ring ${\mathrm{M}}_n(\mathbb{R})$ is equal to $4$ either if $n=3$ or $n>4$. But the case $n=…