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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">cheb</journal-id><journal-title-group><journal-title xml:lang="ru">Чебышевский сборник</journal-title><trans-title-group xml:lang="en"><trans-title>Chebyshevskii Sbornik</trans-title></trans-title-group></journal-title-group><issn pub-type="ppub">2226-8383</issn><publisher><publisher-name>Tula State Lev Tolstoy  Pedagogical University</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.22405/2226-8383-2025-26-2-141-159</article-id><article-id custom-type="elpub" pub-id-type="custom">cheb-1965</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>Статьи</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="en"><subject>Article</subject></subj-group></article-categories><title-group><article-title>Классификация неразрешимых алгебр Ли с четырехмерными орбитами коприсоединенного представления</article-title><trans-title-group xml:lang="en"><trans-title>Classification of unsolvable Lie algebras with four-dimensional orbits of coadjoint representation</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>Лобзин</surname><given-names>Фёдор Игоревич</given-names></name><name name-style="western" xml:lang="en"><surname>Lobzin</surname><given-names>Fedor Igorevich</given-names></name></name-alternatives><email xlink:type="simple">fiadat@mail.ru</email><xref ref-type="aff" rid="aff-1"/></contrib></contrib-group><aff-alternatives id="aff-1"><aff xml:lang="ru"><institution>МГУ имени М. В. Ломоносова; Московский Центр фундаментальной и прикладной математики</institution><country>Россия</country></aff><aff xml:lang="en"><institution>Lomonosov Moscow State University; Moscow Center of Fundamental&#13;
and Applied Mathematics</institution><country>Russian Federation</country></aff></aff-alternatives><pub-date pub-type="collection"><year>2025</year></pub-date><pub-date pub-type="epub"><day>10</day><month>07</month><year>2025</year></pub-date><volume>26</volume><issue>2</issue><fpage>141</fpage><lpage>159</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Лобзин Ф.И., 2025</copyright-statement><copyright-year>2025</copyright-year><copyright-holder xml:lang="ru">Лобзин Ф.И.</copyright-holder><copyright-holder xml:lang="en">Lobzin F.I.</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://www.chebsbornik.ru/jour/article/view/1965">https://www.chebsbornik.ru/jour/article/view/1965</self-uri><abstract><p>В работе представлена классификация алгебр Ли с четырехмерными орбитами коприсоединенного представления для алгебр Ли, изоморфных полупрямой сумме нетривиальной полупростой алгебры Ли и ненулевого разрешимого идеала.</p></abstract><trans-abstract xml:lang="en"><p>The paper presents a classification of Lie algebras with four-dimensional coadjoint orbits for Lie algebras that are isomorphic to a semidirect sum of a nontrivial semisimple Lie algebra and a nonzero solvable ideal.</p></trans-abstract><kwd-group xml:lang="ru"><kwd>скобка Пуассона</kwd><kwd>алгебра Ли</kwd><kwd>коприсоединенное представление</kwd><kwd>интегрируемые системы.</kwd></kwd-group><kwd-group xml:lang="en"><kwd>Poisson bracket</kwd><kwd>Lie algebra</kwd><kwd>coadjoint representation</kwd><kwd>integrable systems.</kwd></kwd-group></article-meta></front><back><ref-list><title>References</title><ref id="cit1"><label>1</label><citation-alternatives><mixed-citation xml:lang="ru">Арнольд В. 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