“…In contrast, if F is not algebraically closed then the commuting graph of M n (F) might be disconnected, as the example of F = Q, the field of rational numbers, demonstrates, see Akbari, Bidkhori, and Mohammadian [1,Remark 8]. Actually, by [1,Theorem 6], Γ(M n (F)) is connected if and only if for every n-degree field extension K of F there exists a proper intermediate subfield. In particular, for finite field F the graph Γ(M n (F)) is disconnected if and only if n is a prime [1,Corollary 7].…”