#2
4x4
1  0  0  0
1  1  0  0
0  1  1  1
0  0  1 -1

4x4
1  1  0  0
1  0  1  0
1  0  0  1
1 -1 -1 -1
dim4/3;1a
4x4
1  1  0  0
1  0  1  0
0  1  1  0
0  0  0  1

4x4
-1  0  1  0
 1  1  2  0
 0 -1  1  0
 0  0  0  1

