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
Notes on a Problem of H. Cohn
✍ Scribed by András Biró
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 103 KB
- Volume
- 77
- Category
- Article
- ISSN
- 0022-314X
No coin nor oath required. For personal study only.
✦ Synopsis
We prove some partial results concerning the following problem: Assume that F is a finite field, a i is a complex number for each i # F such that a 0 =0, a 1 =1, |a i | =1 for all i # F "[0], and i # F a i+j aÄ i =&1 for all i # F "[0]. Does it follow that the function i Ä a i is a multiplicative character of F ? We prove (in the case |F | =p, p is a prime) on the one hand that there is only a finite number of complex solutions; on the other hand we solve completely a mod p version of the problem. The proofs are mainly elementary, except for applying a theorem of Chevalley from algebraic geometry.
📜 SIMILAR VOLUMES
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 ¥ F f(x) f(x+h)=-1 for h ] 0. We prove that this is the case for finite fields of prime cardinality u
We consider problems in the enumeration of sequences suggested by the problem of determining the number of ways of performing a piano composition (Klavierstu ck XI) by Karlheinz Stockhausen.