Two empty graphs: ( ) Two singleton graphs: ( 0 ) Empty and singleton graphs: Two rings: ( 0 1 2 3 4 ) ( 0 4 3 2 1 ) ( 1 0 4 3 2 ) ( 1 2 3 4 0 ) ( 2 1 0 4 3 ) ( 2 3 4 0 1 ) ( 3 2 1 0 4 ) ( 3 4 0 1 2 ) ( 4 0 1 2 3 ) ( 4 3 2 1 0 ) Two directed rings: ( 0 1 2 3 4 ) ( 1 2 3 4 0 ) ( 2 3 4 0 1 ) ( 3 4 0 1 2 ) ( 4 0 1 2 3 ) Two rings where node parity should be equal: ( 0 1 2 3 4 ) ( 4 3 2 1 0 ) Two rings where edge parity should be equal: ( 0 1 2 3 4 ) ( 0 4 3 2 1 ) Two rings with only one vertex coloring: ( 0 1 2 3 4 ) ( 0 4 3 2 1 ) ( 1 0 4 3 2 ) ( 1 2 3 4 0 ) ( 2 1 0 4 3 ) ( 2 3 4 0 1 ) ( 3 2 1 0 4 ) ( 3 4 0 1 2 ) ( 4 0 1 2 3 ) ( 4 3 2 1 0 ) Two rings with vertex coloring: ( 0 1 2 3 4 ) ( 4 3 2 1 0 ) Two rings with edge coloring: ( 0 1 2 3 4 ) ( 0 4 3 2 1 ) Two rings where node of graph 1 should not be 3 higher than node of graph 2: ( 0 1 2 3 4 ) ( 1 0 4 3 2 ) ( 1 2 3 4 0 ) ( 2 1 0 4 3 ) ( 2 3 4 0 1 ) ( 4 0 1 2 3 ) ( 4 3 2 1 0 ) Two rings with different directedness.