[M, N] -> { S1[i0, i1] -> [i0, i1, 0] : i0 >= 1 and i0 <= N and i1 >= 1 and i1 <= M; S2[i0, i0] -> [i0, i0, 1] : i0 >= 3 and i0 <= N }
[M, N] -> {  : N >= M and M >= 4 }
[M, N] -> { [i, j, k] -> separate[o0] }