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JOURNALS // Problemy Fiziki, Matematiki i Tekhniki (Problems of Physics, Mathematics and Technics) // Archive

PFMT, 2025 Issue 1(62), Pages 87–101 (Mi pfmt1020)

MATHEMATICS

On $\sigma$-local formations of finite groups with bounded $\mathfrak{H}_\sigma$-defect

I. N. Safonova, V. V. Skrundz

Belarusian State University, Minsk

Abstract: Let $\mathfrak{F}$ and $\mathfrak{H}$ be some $\sigma$-local formations of finite groups. Then $\mathfrak{F}/_\sigma\ \mathfrak{H}\cap\mathfrak{F}$ denote the lattice of all $\sigma$-local formations $\mathfrak{X}$ such that $\mathfrak{H}\cap\mathfrak{F}\subseteq\mathfrak{X}\subseteq\mathfrak{F}$. The length of the lattice $\mathfrak{F}/_\sigma\ \mathfrak{H}\cap\mathfrak{F}$ is called a $\mathfrak{H}_\sigma$-defect of the $\sigma$-local formation $\mathfrak{F}$. In particular, if $\mathfrak{H}$ is the formation of all identity groups, then the $\mathfrak{H}_\sigma$-defect of a $\sigma$-local formation $\mathfrak{F}$ is called a $l_\sigma$-length of the formation $\mathfrak{F}$. The general properties of $\mathfrak{H}_\sigma$-defect of $\sigma$-local formations are studied, the description of minimal $\sigma$-local non-$\mathfrak{H}$-formations for an arbitrary $\sigma$-nilpotent $\sigma$-local formation $\mathfrak{H}$ is obtained, the description of the lattice structure of $\sigma$-local formations of $\mathfrak{H}_\sigma$-defect $1$ is given. The descriptions of the lattice structure of reducible $\sigma$-local formations of finite $\mathfrak{H}_\sigma$-defect, as well as the lattice structure of reducible $\sigma$-local formations of finite $l_\sigma$-length are obtained.

Keywords: finite group, $\sigma$-local formation, critical $\sigma$-local formation, $\mathfrak{H}_\sigma$-defect of a $\sigma$-local formation, $l_\sigma$-length of a $\sigma$-local formation.

UDC: 512.542

Received: 14.01.2025

DOI: 10.54341/20778708_2025_1_62_87



© Steklov Math. Inst. of RAS, 2025