begin graph (format of 99-02-28)
| The four-dimensional cube 
| (complete lattice on four points)
vertices = 16
edges = 32
0 1
0 2
0 4
0 8
1 3
1 5
1 9
2 3
2 6
2 10
4 5
4 6
4 12
8 9
8 10
8 12
3 7
3 11
5 7
5 13
9 11
9 13
6 7
6 14
10 11
10 14
12 13
12 14
7 15
11 15
13 15
14 15
end graph