Then we have l = 2, i.e., G − V(M) has just two components with n − 2 vertices, and so |M| = 2. Let em denote the
number of edges between G − V(M) and V(M). According to (n + 1)-regularity of G, each vertex in V(G) V(M)
is adjacent to every vertex in V(M). So em = 4(2n −4) = 8n −16. Furthermore, counting the number of edges from
V(M) to V(G) V(M), we have em n · |V(M)| = 4n. Thus we have 8n −16 4n, implying n 4, contradicting
the fact that n is odd and n 6= 3. The proof is completed.