Equation Icon  1 -3/2 +1/2 1 -1/2 -1/2 D2 n1 =_ ---nc [D(n c )] n1 +--nc D(n c n1) (217) 2 2 ~~ + 1-n-c1 [Dn1] (218) 2 1- -1 2 = - 2 nc k n1. (219)