Incidence matrix according to symbol extension

x3o:s3s6s   (N,M → ∞)

 N |  6M |  9M  6M |  8M M  verf: snathat
---+-----+---------+------
 2 | 3NM |   3   2 |   4 1
---+-----+---------+------
 3 |   3 | 3NM   * |   2 0
 3 |   3 |   * 2NM |   1 1
---+-----+---------+------
 4 |   6 |   3   1 | 2NM *  tet
 M |  3M |   0  2M |   * N  trat