Abstract
We settle the isomorphism problem for finite cyclic projective planes by proving the following analogue of the Bays–Lambossy theorem: two cyclic projective planes of order n are isomorphic if and only if they are multiplier equivalent, that is, if and only if the associated difference sets in \({\mathbb{Z}_{n^2+n+1}}\) are equivalent. In fact, we establish a more general result for abelian groups, where multipliers are replaced by group automorphisms.
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Jungnickel, D. The isomorphism problem for abelian projective planes. AAECC 19, 195–200 (2008). https://doi.org/10.1007/s00200-008-0070-4
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DOI: https://doi.org/10.1007/s00200-008-0070-4