Abstract
We show that every quasitrivial n-ary semigroup is reducible to a binary semigroup, and we provide necessary and sufficient conditions for such a reduction to be unique. These results are then refined in the case of symmetric n-ary semigroups. We also explicitly determine the sizes of these classes when the semigroups are defined on finite sets. As a byproduct of these enumerations, we obtain several new integer sequences.
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Acknowledgements
Both authors would like to thank Jean-Luc Marichal and the anonymous referee for their useful comments and insightful remarks that helped improving the current paper.
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Jimmy Devillet is supported by the Luxembourg National Research Fund under the project PRIDE 15/10949314/GSM.
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Couceiro, M., Devillet, J. Every quasitrivial n-ary semigroup is reducible to a semigroup. Algebra Univers. 80, 51 (2019). https://doi.org/10.1007/s00012-019-0626-0
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DOI: https://doi.org/10.1007/s00012-019-0626-0