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arXiv · 2610.05415

The group class SJ is not countably recognizable

M. Brescia·B. G. Di Siena·E. Ingrosso·M. Trombetti
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Abstract

A group is an {\it $\SJ$-group} if it admits a general abelian series all of whose terms are subnormal of finite defect in the whole group. We construct a group $G$ which is not an~\hbox{$\SJ$-group}, although every countable subgroup of $G$ is an $\SJ$-group.

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M. Brescia, B. G. Di Siena, E. Ingrosso, M. Trombetti. 2026-10-04. The group class SJ is not countably recognizable. https://arxiv.org/abs/2610.05415

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