Addendum to: commensurations of the Johnson kernel

Let K(S) be the subgroup of the extended mapping class group, Mod(S), generated by Dehn twists about separating curves. In our earlier paper, we showed that Comm(K(S))≅Aut(K(S))≅Mod(S) when S is a closed, connected, orientable surface of genus g ≥ 4. By modifying our original proof, we show that the same result holds for g ≥ 3, thus confirming Farb’s conjecture in all cases (the statement is not true for g ≤ 2)