Let D be a (v, k, λ) difference set over an abelian group G with even n = k - λ. Assume that t ∈ N satisfies the congruences t = qfii (mod exp(G)) for each prime divisor qi of n/2 and some integer fi. In  it was shown that t is a multiplier of D provided that n > λ, (n/2, λ) = 1 and (n/2, v) = 1. In this paper we show that the condition n > λ may be removed. As a corollary we obtain that in the case of n = 2pa when p is a prime, p should be a multiplier of D. This answers an open question mentioned in .
- Abelian group
- Difference set
ASJC Scopus subject areas
- Algebra and Number Theory
- Discrete Mathematics and Combinatorics