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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="elpub" pub-id-type="custom">mathnas-66</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>К теореме К. Дёрка</article-title><trans-title-group xml:lang="en"><trans-title>To the theorem of K. Doerk</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>Мурашко</surname><given-names>В. И.</given-names></name><name name-style="western" xml:lang="en"><surname>Murashka</surname><given-names>V. I.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Гомель</p></bio><bio xml:lang="en"><p>Gomel</p></bio><email xlink:type="simple">mvimath@yandex.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>Васильев</surname><given-names>А. Ф.</given-names></name><name name-style="western" xml:lang="en"><surname>Vasil’ev</surname><given-names>A. F.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Гомель</p></bio><bio xml:lang="en"><p>Gomel</p></bio><email xlink:type="simple">ormation56@mail.ru</email><xref ref-type="aff" rid="aff-1"/></contrib></contrib-group><aff-alternatives id="aff-1"><aff xml:lang="ru"><institution>Гомельский государственный университет им. Ф. Скорины</institution></aff><aff xml:lang="en"><institution>Francisk Skorina Gomel State University</institution></aff></aff-alternatives><pub-date pub-type="collection"><year>2025</year></pub-date><pub-date pub-type="epub"><day>30</day><month>06</month><year>2025</year></pub-date><volume>33</volume><issue>1</issue><fpage>28</fpage><lpage>33</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Мурашко В.И., Васильев А.Ф., 2025</copyright-statement><copyright-year>2025</copyright-year><copyright-holder xml:lang="ru">Мурашко В.И., Васильев А.Ф.</copyright-holder><copyright-holder xml:lang="en">Murashka V.I., Vasil’ev A.F.</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/66">https://mathnas.ejournal.by/jour/article/view/66</self-uri><abstract><p>Для конечной группы $G$ и ее максимальной подгруппы $M$ мы доказали, что обобщенная высота Фиттинга группы $G$ минус  обобщенная высота Фиттинга подгруппы $M$ не превосходит 2, а не-$p$-разрешимая длина группы $G$ минус не-$p$-разрешимая длина подгруппы $M$ не превосходит 1. Мы построили наследственную насыщенную формацию $\mathfrak{F}$ так, что $\{n_\sigma(G, \mathfrak{F})-n_\sigma(M, \mathfrak{F})\mid G$ конечна $\sigma$-разрешима и $M$ является максимальной подгруппой группы $G\}=\mathbb{N}\cup\{0\}$, где $n_\sigma(G, \mathfrak{F})$ обозначает $\sigma$-нильпотентную длину $\mathfrak{F}$-корадикала группы $G$. Эта конструкция показывает, что результаты об обобщенных длинах максимальных подгрупп, опубликованные в Math. Nachr. (1994) и Mathematics (2020), являются некорректными.</p></abstract><trans-abstract xml:lang="en"><p>For a finite group $G$ and its maximal subgroup $M$ we proved that the generalized Fitting height of $G$ minus the generalized Fitting height of $M$ is not greater than 2 and the non-$p$-soluble length of $G$ minus the non-$p$-soluble length of $M$ is not greater than 1. We constructed a hereditary saturated formation $\mathfrak{F}$ such that $\{n_\sigma(G, \mathfrak{F})-n_\sigma(M, \mathfrak{F})\mid G$ is finite $\sigma$-soluble and $M$ is a maximal subgroup of $G\}=\mathbb{N}\cup\{0\}$ where $n_\sigma(G, \mathfrak{F})$ denotes the $\sigma$-nilpotent length of the $\mathfrak{F}$-residual of  $G$.</p><p>This construction shows the results about the generalized lengths of maximal subgroups published in Math. Nachr. (1994) and Mathematics (2020) are not correct.</p></trans-abstract><kwd-group xml:lang="ru"><kwd>конечная группа</kwd><kwd>обобщенная подгруппа Фиттинга</kwd><kwd>обобщенная высота Фиттинга</kwd><kwd>не-$p$-разрешимая длина</kwd><kwd>наследственный радикал Плоткина</kwd><kwd>$\sigma$-нильпотентная группа</kwd></kwd-group><kwd-group xml:lang="en"><kwd>finite group</kwd><kwd>the generalized Fitting subgroup</kwd><kwd>the generalized Fitting height</kwd><kwd>the non-$p$-soluble length</kwd><kwd>hereditary Plotkin radical</kwd><kwd>$\sigma$-nilpotent group</kwd></kwd-group><funding-group><funding-statement xml:lang="en">The work was supported by BRFFR grant no. Φ23PHΦ-237.</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">Cannon J. J., Eick B., Leedham-Green C. R. Special polycyclic generating sequences for finite soluble groups. J. Symb. 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