由于基象a(a)∈Ⅳ(F)(i=1,2,…,m),所以它们可 经的基a1,a2,…,cn线性表出,即有 o(a=ad+a2a2+.+and (a2)=a12C1+a2ax2+…+anCn(4.30 o(an)=a1n1+a2a2+…+a oax1,,…,=[o(a1),o(a2),…,(a1) (4.31) 2021/2/202021/2/20 32 由于基象s(ai )V(F),(i=1,2,...,n), 所以它们可 经V(F)的基a1 ,a2 ,...,an线性表出, 即有 1 11 1 21 2 1 2 12 1 22 2 1 1 1 2 2 ( ) ( ) (4.30) ( ) n n n n n n n nn n a a a a a a a a a s a a a a s a a a a s a a a a  = + + +  = + + +    = + + + 记 s[a1 ,a2 ,...,an ]=[s(a1 ),s(a2 ),...,s(an )]. (4.31)