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