Abstract
We say that \((x,y,z)\in Q^3\) is an associative triple in a quasigroup \((Q,*)\) if \((x*y)*z=x*(y*z)\). Let a(Q) denote the number of associative triples in Q. It is easy to show that \(a(Q)\ge |Q|\), and we call the quasigroup maximally nonassociative if \(a(Q)= |Q|\). It was conjectured that maximally nonassociative quasigroups do not exist when \(|Q|>1\). Drápal and Lisoněk recently refuted this conjecture by proving the existence of maximally nonassociative quasigroups for a certain infinite set of orders |Q|. In this paper we prove the existence of maximally nonassociative quasigroups for a much larger set of orders |Q|. Our main tools are finite fields and the Weil bound on quadratic character sums. Unlike in the previous work, our results are to a large extent constructive.
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Communicated by D. Panario.
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Research was supported in part by the Natural Sciences and Engineering Research Council of Canada (NSERC).
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Lisoněk, P. Maximal nonassociativity via fields. Des. Codes Cryptogr. 88, 2521–2530 (2020). https://doi.org/10.1007/s10623-020-00800-4
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DOI: https://doi.org/10.1007/s10623-020-00800-4