On a theorem of Ganley
Let D be a relative difference with parameters (n,n,n,1) in an Abelian group G of even order \(n^ 2\). By a result of Ganley [\textit{M. J. Ganley}, Arch. Math. 27, 93-98 (1976; Zbl 0323.20046)], n is necessarily a power of 2 and G is a direct sum of copies of \({\mathbb{Z}}_ 4\). We present a simple (and much shorter) alternative proof of this result, based on a geometric argument and a simple characterization of the groups in question.
scientific article; zbMATH DE number 4077234