Ciolan, Alexandru and García-Sánchez, Pedro A. and Herrera-Poyatos, Andrés and Moree, Pieter
(2021)
*Cyclotomic exponent sequences of numerical semigroups.*
MPIM Preprint Series 2021 (5).

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## Abstract

We study the cyclotomic exponent sequence of a numerical semigroup $S,$ and we compute its values at the gaps of $S,$ the elements of $S$ with unique representations in terms of minimal generators, and the Betti elements $b\in S$ for which the set $\{a \in \operatorname{Betti}(S) : a \le_{S}b\}$ is totally ordered with respect to $\le_S$ (we write $a \le_S b$ whenever $a - b \in S,$ with $a,b\in S$).

This allows us to characterize certain semigroup families, such as Betti-sorted or Betti-divisible numerical semigroups, as well as numerical semigroups with a unique Betti element, in terms of their cyclotomic exponent sequences.

Our results also apply to \textit{cyclotomic numerical semigroups}, which are numerical semigroups with a finitely supported cyclotomic exponent sequence. We show that cyclotomic numerical semigroups with certain cyclotomic exponent sequences are complete intersections, thereby making progress towards proving the conjecture of Ciolan, Garc\'ia-S\'anchez and Moree (2016) stating that $S$ is cyclotomic if and only if it is a complete intersection.

Item Type: | MPIM Preprint |
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Subjects: | 1 Discrete mathematics / algebra > 11-XX Number theory 1 Discrete mathematics / algebra > 20-XX Group theory and generalizations |

Divisions: | Research > Preprints |

Depositing User: | Andrea Kohlhuber |

Date Deposited: | 11 Feb 2021 11:40 |

Last Modified: | 11 Feb 2021 11:41 |

URI: | https://archive.mpim-bonn.mpg.de/id/eprint/4198 |

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