English

Element orders in extraspecial groups

Group Theory 2024-05-08 v1

Abstract

By using the structure and some properties of extraspecial and generalized/almost extraspecial pp-groups, we explicitly determine the number of elements of specific orders in such groups. As a consequence, one may find the number of cyclic subgroups of any (generalized/almost) extraspecial group. For a finite group GG, the ratio of the number of cyclic subgroups to the number of subgroups is called the cyclicity degree of GG and is denoted by cdeg(G)cdeg(G). We show that the set containing the cyclicity degrees of all finite groups is dense in [0,1][0, 1]. This is equivalent to giving an affirmative answer to the following question posed by T\'{o}th and T\u{a}rn\u{a}uceanu: ``For every a[0,1]a\in [0, 1], does there exist a sequence (Gn)n1(G_n)_{n\geq 1} of finite groups such that limncdeg(Gn)=a\displaystyle\lim_{n\to\infty} cdeg(G_n)=a?". We show that such sequences are formed of finite direct products of extraspecial groups of a specific type.

Keywords

Cite

@article{arxiv.2405.04141,
  title  = {Element orders in extraspecial groups},
  author = {Mihai-Silviu Lazorec},
  journal= {arXiv preprint arXiv:2405.04141},
  year   = {2024}
}

Comments

accepted for publication in Acta Math. Hung

R2 v1 2026-06-28T16:19:12.360Z