(Ir)Reducibility of some commuting varieties associated with involutions

Here we prove that a commuting variety associated with a symmetric pair (g, g_0) is irreducible for (so_{n+m}, so_n + so_m) and reducible for (gl_{n+m}, {gl}n + gl_m) with n>m, (so{2n}, gl_n) with odd n, (E_6, {so}_{10} + k).