Semi-regular relative difference sets with large forbidden subgroups

  • Authors:
  • Tao Feng;Qing Xiang

  • Affiliations:
  • School of Mathematical Sciences, Peking University, Beijing 100871, China;Department of Mathematical Sciences, University of Delaware, Newark, DE 19716, USA

  • Venue:
  • Journal of Combinatorial Theory Series A
  • Year:
  • 2008

Quantified Score

Hi-index 0.00

Visualization

Abstract

Motivated by a connection between semi-regular relative difference sets and mutually unbiased bases, we study relative difference sets with parameters (m,n,m,m/n) in groups of non-prime-power orders. Let p be an odd prime. We prove that there does not exist a (2p,p,2p,2) relative difference set in any group of order 2p^2, and an abelian (4p,p,4p,4) relative difference set can only exist in the group Z"2^2xZ"3^2. On the other hand, we construct a family of non-abelian relative difference sets with parameters (4q,q,4q,4), where q is an odd prime power greater than 9 and q=1(mod4). When q=p is a prime, p9, and p=1(mod4), the (4p,p,4p,4) non-abelian relative difference sets constructed here are genuinely non-abelian in the sense that there does not exist an abelian relative difference set with the same parameters.