对于将有限域上的自对偶基概念推广到了更一般的弱自对偶的情形,给出了有限域上存在这类正规基的一个充要条件:设q为素数幂,E=Fq^n为q元域F=Fq的n次扩张,N={αi=α^q^i|i=0,1,…,n-1)为E在F上的一组正规基.则存在c∈F^*及r,0≤r≤n-1,使得β=Cαr生成N的对偶基的充要条件是以下三者之一成立;(1)q为偶数且n≠0(mod4);(2)n与q均为奇数;(3)q为奇数,n为偶数,(-1)为F中的非平方元旦r为奇数.
This paper expands self-dual bases to general weakly self-dual bases and gets a sufficient and necessary condition for the finite field which has a weakly self-dual normal basis as the following: Let q be the power of a prime, E = Fq^n be the n-dimensional extension of the finite field F = Fq, and N = {αi = α^q^i | i = 0, 1,... , n - 1} be a normal basis of E over F. Then there exist some c ∈ F^* and some r, 0 ≤ r ≤n - 1 such that β = cαr generates the dual of N if and only if either q is even and n ≠ 0 (mod 4); or n and q are odd; or q is odd, n is even, (-1) is a nonsquare in F and r is odd.