engGrau, J.M.Oller-Marcén, A.M.Tasis, C.On the diameter of the commuting graph of the full matrix ring over the real numbersART-2017-98148In a recent paper C. Miguel proved that the diameter of the commuting graph of the matrix ring Mn(R) is equal to 4 if either n = 3 or n = 5. But the case n = 4 remained open, since the diameter could be 4 or 5. In this work we close the problem showing that also in this case the diameter is 4.2017http://zaguan.unizar.es/record/60697http://zaguan.unizar.es/record/60697oai:zaguan.unizar.es:60697Bulletin of the Iranian Mathematical Society 43, 1 (2017), 217-221by-nchttp://creativecommons.org/licenses/by-nc/3.0/es/info:eu-repo/semantics/openAccess