In an undirected graph, (i,j) means that node i and node j are connected with an undirected edge.
The nodes are numbered from 0 to 11, and the edges are: (11,9) (0,7) (10,0) (0,2) (1,0) (11,4) (3,8) (2,4) (1,5) (0,4) (6,2) (0,11) (0,3) (7,3) (3,1).