PD ( X ( 1 , 4 , 2 , 5 ) , X ( 3 , 6 , 4 , 1 ) , X ( 5 , 2 , 6 , 3 ) ) {\displaystyle {\text{PD}}(X(1,4,2,5),X(3,6,4,1),X(5,2,6,3))}