A New Construction of Central Relative (p
a
, p
a
, p
a
, 1)-Difference Sets |
| |
Authors: | K J Horadam P Udaya |
| |
Institution: | (1) Department of Mathematics, RMIT University, GPO Box 2476V, Melbourne, VIC 3001, Australia |
| |
Abstract: | Semiregular relative difference sets (RDS) in a finite group E which avoid a central subgroup C are equivalent to orthogonal cocycles. For example, every abelian semiregular RDS must arise from a symmetric orthogonal cocycle, and vice versa. Here, we introduce a new construction for central (p
a
, p
a
, p
a
, 1)-RDS which derives from a novel type of orthogonal cocycle, an LP cocycle, defined in terms of a linearised permutation (LP) polynomial and multiplication in a finite presemifield. The construction yields many new non-abelian (p
a
, p
a
, p
a
, 1)-RDS. We show that the subset of the LP cocycles defined by the identity LP polynomial and multiplication in a commutative semifield determines the known abelian (p
a
, p
a
, p
a
, 1)-RDS, and give a second new construction using presemifields.We use this cohomological approach to identify equivalence classes of central (p
a
, p
a
, p
a
, 1)-RDS with elementary abelian C and E/C. We show that for p = 2, a 3 and p = 3, a 2, every central (p
a
, p
a
, p
a
, 1)-RDS is equivalent to one arising from an LP cocycle, and list them all by equivalence class. For p = 2, a = 4, we list the 32 distinct equivalence classes which arise from field multiplication. We prove that, for any p, there are at least a equivalence classes of central (p
a
, p
a
, p
a
, 1)-RDS, of which one is abelian and a – 1 are non-abelian. |
| |
Keywords: | (p
a
p
a
p
a
1)-RDS relative difference set orthogonal cocycle semifield linearised permutation polynomial |
本文献已被 SpringerLink 等数据库收录! |
|