Because in the region d 1-D2 = {(x, y) | 0.

So j 1-J2

j 1-J3 =∫∫(d 1-D3)(x-y)^( 1/3)dxdy

Because in the region d 1-D3 = {(x, y) | 0; 0,(x-y)^( 1/3)>； 0

So j1-J3 >; 0，j 1 & gt； J3

All in all, JBOY3.