Page 4: In the seventh paragraph of section two (the one that begins "We may
now verify"), the iterative algorithm presented for reducing the rank of a
tiling is not correct. In order to be assured that the v_i that is chosen
is one whose height can be reduced, it is not sufficient that v_i be a vertex
at which h_{T_i} achieves its maximum value. Fortunately, the proof is easily
fixed: simply require that, among all those vertices that maximize h_{T_i},
v_i maximizes H_{T_i}. Then the proof goes through.