... NK 1 × K2[a, b]K Rnf ∈ C[0, 1] nk fBk(x 1 , ··· ,xn)=0≤p 1 ,···,pn≤kCp 1 k···Cpnkf(p 1 k, ··· ,pnk)xp 1 1···xpnn (1 x 1 )k−p 1 ··· (1 xn)k−pn.(Bk) fA = ... TPk(x)=ak,0+Nkp =1 (ak,psin(2πpxT)+bk,pcos(2πpxT)).R T>0C[0,T]RnnK 1 ⊂ Rn 1 K2⊂ Rn2A 1 A2K 1 ,K2A 1 A2f ∈ C(K 1 × K2)ki =1 gi(x)hi(y)gi∈A 1 ,hi∈A2,k ∈ NK 1 × ... ,fm(x 1 , ··· ,xn))g(y)=(g 1 (y 1 , ··· ,ym), ··· ,gp(y 1 , ··· ,ym))y = f(x)h(x)=g ◦f(x)=(h 1 (x 1 , ··· ,xn), ··· ,hp(x 1 , ··· ,xn))∂h 1 ∂x 1 ···∂h 1 ∂xn···...