P :=
6 7
1   1    1   -2   -1   -1    4
1   0    0    1    1    1   -4
1   0    0   -2   -1   -1    6
1   2    0   -4   -3   -2   10
1  -1    0    2    1    1   -4
1  -3   -1    6    4    2  -12
;
assert((lattice_width(P)) = { 1 });
