Bo =(出+N, Yo=XII0+Eo LnL(Yo)=c+Lno-tr'(Yo-XTI)'(Yo-XII) Y0 X 1 0 1 0 1 =  +  LnL c Ln tr n (Y ) (Y X ) (Y X ) 0 1 2 0 1 1 2 0 1 0 1 0 1 0 1 0 1 = + − −  − − −     Y1 = 0 0 1      (Y , X )  + 0 0    (Y , X ) 0 0 1 0 0 1 1 0          + =