元路径

关系矩阵

A F 1 D

M A F M F D ( i , j )

A F 1 A

M A F M F A ( i , j )

D F 1 D

M D F M F D ( i , j )

F 1 A F

M F A M A F ( i , j )

F 1 D F

M F D M D F ( i , j )