Abstract
LetD be a relative difference with parameters (n, n, n, 1) in an abelian groupG of even ordern 2. By a result of Ganley [3],n is necessarily a power of 2 andG is a direct sum of copies of ℤ4. We present a simple (and much shorter) alternative proof of this result, based on a geometric argument and a simple characterisation of the groups in question.
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Jungnickel, D. On a theorem of Ganley. Graphs and Combinatorics 3, 141–143 (1987). https://doi.org/10.1007/BF01788537
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DOI: https://doi.org/10.1007/BF01788537