Hamilton-圈

G 2

G 3

G 4

完美匹配的交

M 3 M 4 =

M 2 M 4 =

M 2 M 3 =

完美匹配的不交并

M 3 ˙ M 4

M 2 ˙ M 4

M 2 ˙ M 3