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<article article-type="research-article" dtd-version="1.3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xml:lang="ru"><front><journal-meta><journal-id journal-id-type="publisher-id">mathnas</journal-id><journal-title-group><journal-title xml:lang="ru">Труды Института математики НАН Беларуси</journal-title><trans-title-group xml:lang="en"><trans-title>Proceedings of the Institute of Mathematics of the NAS of Belarus</trans-title></trans-title-group></journal-title-group><issn pub-type="ppub">1812-5093</issn><publisher><publisher-name>Институт математики НАН Беларуси</publisher-name></publisher></journal-meta><article-meta><article-id custom-type="edn" pub-id-type="custom">OLYGHB</article-id><article-id custom-type="elpub" pub-id-type="custom">mathnas-97</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research Article</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="ru"><subject>АЛГЕБРА И ТЕОРИЯ ЧИСЕЛ</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="en"><subject>ALGEBRA AND NUMBER THEORY</subject></subj-group></article-categories><title-group><article-title>Приводимые τ-замкнутые σ-локальные формации конечных групп с заданной структурой подформаций</article-title><trans-title-group xml:lang="en"><trans-title>Reducible τ-closed σ-local formations of finite groups with a given structure of subformations</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Скрундь</surname><given-names>В. В.</given-names></name><name name-style="western" xml:lang="en"><surname>Skrundz</surname><given-names>V. V.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Минск</p></bio><email xlink:type="simple">vallik@mail.ru</email><xref ref-type="aff" rid="aff-1"/></contrib><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Сафонова</surname><given-names>И. Н.</given-names></name><name name-style="western" xml:lang="en"><surname>Safonova</surname><given-names>I. N.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Минск</p></bio><bio xml:lang="en"><p>Minsk</p></bio><email xlink:type="simple">in.safonova@mail.ru</email><xref ref-type="aff" rid="aff-1"/></contrib></contrib-group><aff-alternatives id="aff-1"><aff xml:lang="ru"><institution>Белорусский государственный университет</institution></aff><aff xml:lang="en"><institution>Belarusian State University</institution></aff></aff-alternatives><pub-date pub-type="collection"><year>2025</year></pub-date><pub-date pub-type="epub"><day>05</day><month>01</month><year>2026</year></pub-date><volume>33</volume><issue>2</issue><fpage>36</fpage><lpage>53</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Скрундь В.В., Сафонова И.Н., 2026</copyright-statement><copyright-year>2026</copyright-year><copyright-holder xml:lang="ru">Скрундь В.В., Сафонова И.Н.</copyright-holder><copyright-holder xml:lang="en">Skrundz V.V., Safonova I.N.</copyright-holder><license xml:lang="ru" license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>Данная работа распространяется под лицензией Creative Commons Attribution 4.0.</license-p></license><license xml:lang="en" license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>This work is licensed under a Creative Commons Attribution 4.0 License.</license-p></license></permissions><self-uri xlink:href="https://mathnas.ejournal.by/jour/article/view/97">https://mathnas.ejournal.by/jour/article/view/97</self-uri><abstract><p>Пусть $\mathfrak{F}$ и $\mathfrak{H}$ – некоторые $\tau$-замкнутые $\sigma$-локальные формации конечных групп. Через $\mathfrak{F}/^\tau_\sigma\mathfrak{H}\cap\mathfrak{F}$ обозначают решетку всех $\tau$-замкнутых $\sigma$-локальных формаций $\mathfrak{X}$ таких, что $\mathfrak{H}\cap\mathfrak{F}\subseteq \mathfrak{X}\subseteq \mathfrak{F}.$ Длину решетки $\mathfrak{F}/^\tau_\sigma\mathfrak{H}\cap\mathfrak{F}$ называют {\it $\mathfrak H^\tau_\sigma$-дефектом}, а при $\mathfrak{H}=(1)$ – формация всех единичных групп, {\it $l^\tau_\sigma$-длиной} формации $\mathfrak{F}$. Изучены общие свойства $\mathfrak H^\tau_\sigma$-дефекта $\tau$-замкнутых $\sigma$-локальных формаций, получено описание структурного строения приводимых $\tau$-замкнутых $\sigma$-локальных формаций, имеющих $\mathfrak H^\tau_\sigma$-дефект $\leq 2$ и $l^\tau_\sigma$-длину $\leq 3$.</p></abstract><trans-abstract xml:lang="en"><p>Let $\mathfrak{F}$ and $\mathfrak{H}$ be some $\tau$-closed $\sigma$-local formations of finite groups. By $\mathfrak{F}/^\tau_\sigma\mathfrak{H}\cap\mathfrak{F}$ we denote the lattice of all $\tau$-closed $\sigma$-local formations $\mathfrak{X}$ such that $\mathfrak{H}\cap\mathfrak{F}\subseteq \mathfrak{X}\subseteq \mathfrak{F}.$ The length of the lattice $\mathfrak{F}/^\tau_\sigma\mathfrak{H}\cap\mathfrak{F}$ is called the {\it $\mathfrak H^\tau_\sigma$-defect}, and for $\mathfrak{H}=(1)$ it is the formation of all identity groups, {\it $l^\tau_\sigma$-length} of $\mathfrak{F}$. The general properties of the $\mathfrak H^\tau_\sigma$-defect of $\tau$-closed $\sigma$-local formations are studied, and a description of the structural structure of reducible $\tau$-closed $\sigma$-local formations with $\mathfrak H^\tau_\sigma$-defect $\leq 2$ and $l^\tau_\sigma$-length $\leq 3$ is obtained.</p></trans-abstract><kwd-group xml:lang="ru"><kwd>конечная группа</kwd><kwd>подгрупповой функтор</kwd><kwd>$\tau$-замкнутая $\sigma$-локальная формация</kwd><kwd>критическая $\tau$-замкнутая $\sigma$-локальная формация</kwd><kwd>$\mathfrak H^\tau_\sigma$-дефект формации</kwd><kwd>$l^\tau_\sigma$-длина формации</kwd></kwd-group><kwd-group xml:lang="en"><kwd>finite group</kwd><kwd>subgroup functor</kwd><kwd>$\tau$-closed $\sigma$-local formation</kwd><kwd>critical $\tau$-closed $\sigma$-local formation</kwd><kwd>$\mathfrak H^\tau_\sigma$-defect of $\tau$-closed $\sigma$-local formation</kwd></kwd-group><funding-group><funding-statement xml:lang="ru">The research was carried out within the framework of the State Scientific Research Program “Convergence–2025” with the financial support of the Ministry of Education of the Republic of Belarus (project 20211328)</funding-statement><funding-statement xml:lang="en">The research was carried out within the framework of the State Scientific Research Program “Convergence–2025” with the financial support of the Ministry of Education of the Republic of Belarus (project 20211328)</funding-statement></funding-group></article-meta></front><back><ref-list><title>References</title><ref id="cit1"><label>1</label><citation-alternatives><mixed-citation xml:lang="ru">Shemetkov L. 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