content_image/302592.jpg content_image/302589.jpg content_image/302590.jpg
<img src='content_image/302592.jpg'>

respectively. Then for any given k , each term in the second line of (25) insert the two gluons corresponding to ( N + 1)$_{h}$ at the positions between 1, k and k , i respectively. The C part then becomes 

<img src='content_image/302589.jpg'>

where P$_{3}$ are the insertions of the four gluons corresponding to the two gravitons ( N + 2)$_{h}$ and ( N + 1)$_{h}$. In these insertions, two gluons corresponding to ( N + 2)$_{h}$ are inserted at the positions between 1, l and l , i respectively, then two gluons corresponding to ( N + 1)$_{h}$ are inserted at the positions between 1, k and k , i respectively( See Fig. 4). 

After considering all the contributions from A , B and C , we give the D$_{2}$ relation 

<img src='content_image/302590.jpg'>

