Let f be a complex-valued function on a finite field F such that f(0)=0, f(1)=1, and |f(x)|=1 for x ] 0. H. Cohn asked if it follows that f is a nontrivial multiplicative character provided that ; x ยฅ F f(x) f(x+h)=-1 for h ] 0. We prove that this is the case for finite fields of prime cardinality u
On character sums and the exceptional set of a congruence problem
โ Scribed by M.Z. Garaev; A.A. Karatsuba
- Publisher
- Elsevier Science
- Year
- 2005
- Tongue
- English
- Weight
- 184 KB
- Volume
- 114
- Category
- Article
- ISSN
- 0022-314X
No coin nor oath required. For personal study only.
โฆ Synopsis
We prove an estimate of character sums. This bound and the method of solving multiplicative ternary problems are used to obtain new results about the cardinality of an exceptional set of a congruence problem modulo a prime p. In particular, we show that "almost all" residue classes modulo p are representable in the form xy (mod p), where max{x, y} p 5 8 +ฮต .
๐ SIMILAR VOLUMES
Cohn's problem on character sums (see , p. 202) asks whether a multiplicative character on a finite field can be characterized by a kind of two level autocorrelation property. Let f be a map from a finite field F to the complex plane such that f (0)=0, f (1)=1, and | f (:)| =1 for all :{0. In this p