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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">10.22405/2226-8383-2026-27-1-77-96</article-id><article-id custom-type="elpub" pub-id-type="custom">cheb-2185</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>Явное решение критических подсистем интегрируемого семейства Ковалевской – Чаплыгина</article-title><trans-title-group xml:lang="en"><trans-title>Explicit solution of the critical subsystems for the Kovalevskaya-Chaplygin integrable family</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>Николаенко</surname><given-names>Станислав Сергеевич</given-names></name><name name-style="western" xml:lang="en"><surname>Nikolaenko</surname><given-names>Stanislav Sergeevich</given-names></name></name-alternatives><bio xml:lang="ru"><p>кандидат физико-математических наук</p></bio><bio xml:lang="en"><p>candidate of physical and mathematical sciences</p></bio><email xlink:type="simple">nikolaenko.s@phystech.edu</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>Рябов</surname><given-names>Павел Евгеньевич</given-names></name><name name-style="western" xml:lang="en"><surname>Ryabov</surname><given-names>Pavel Evgenyevich</given-names></name></name-alternatives><bio xml:lang="ru"><p>доктор физико-математических наук</p></bio><bio xml:lang="en"><p>doctor of physical and mathematical sciences</p></bio><email xlink:type="simple">ryabov.pe@mipt.ru</email><xref ref-type="aff" rid="aff-2"/></contrib><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Соколов</surname><given-names>Сергей Викторович</given-names></name><name name-style="western" xml:lang="en"><surname>Sokolov</surname><given-names>Sergey Viktorovich</given-names></name></name-alternatives><bio xml:lang="ru"><p>доктор физико-математических наук</p></bio><bio xml:lang="en"><p>doctor of physical and mathematical sciences</p></bio><email xlink:type="simple">sokolov.sv@phystech.edu</email><xref ref-type="aff" rid="aff-3"/></contrib></contrib-group><aff-alternatives id="aff-1"><aff xml:lang="ru"><institution>физико-технический институт (национальный исследовательский университет)</institution><country>Россия</country></aff><aff xml:lang="en"><institution>Moscow Institute of Physics and Technology (National Research University)</institution><country>Russian Federation</country></aff></aff-alternatives><aff-alternatives id="aff-2"><aff xml:lang="ru"><institution>Московский физикотехнический институт (национальный исследовательский университет)</institution><country>Россия</country></aff><aff xml:lang="en"><institution>Moscow Institute of Physics and Technology (National Research University)</institution><country>Russian Federation</country></aff></aff-alternatives><aff-alternatives id="aff-3"><aff xml:lang="ru"><institution>Московский физико-технический институт (национальный исследовательский университет)</institution><country>Россия</country></aff><aff xml:lang="en"><institution>Moscow Institute of Physics and Technology (National Research University)</institution><country>Russian Federation</country></aff></aff-alternatives><pub-date pub-type="collection"><year>2026</year></pub-date><pub-date pub-type="epub"><day>15</day><month>04</month><year>2026</year></pub-date><volume>27</volume><issue>1</issue><fpage>77</fpage><lpage>96</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Николаенко С.С., Рябов П.Е., Соколов С.В., 2026</copyright-statement><copyright-year>2026</copyright-year><copyright-holder xml:lang="ru">Николаенко С.С., Рябов П.Е., Соколов С.В.</copyright-holder><copyright-holder xml:lang="en">Nikolaenko S.S., Ryabov P.E., Sokolov S.V.</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/2185">https://www.chebsbornik.ru/jour/article/view/2185</self-uri><abstract><p>Работа посвящена изучению фазовой топологии интегрируемого случая Ковалевской – Чаплыгина в динамике твёрдого тела. Этот случай, с одной стороны, является обобщением классических случаев Ковалевской и Чаплыгина, а с другой стороны, вписывается в 6-параметрическое семейство гамильтоновых систем с двумя степенями свободы, интегрируемых при нулевом значении интеграла площадей. Для рассматриваемой задачи детально изучены критические подсистемы — системы с одной степенью свободы, являющиеся ограничением исходной гамильтоновой системы на критическое множество отображения момента. Получена явная параметризация критического множества, что как следствие даёт бифуркационную диаграмму и образ отображения момента. Для всех пяти критических подсистем при каждом значении интеграла энергии и параметра задачи получено их явноерешение в эллиптических квадратурах. Кроме того, для каждой критической подсистемы описаны бифуркации интегральных траекторий при изменении уровня энергии. Оказалось, что все нетривиальные бифуркации седлового типа исчерпываются 2-атомами 𝐵 и 𝐶2 (стандартные перестройки двух критических окружностей в одну и двух окружностей в две соответственно).</p></abstract><trans-abstract xml:lang="en"><p>In this paper we study the phase topology for the Kovalevskaya – Chaplygin integrable case in rigid body dynamics. On the one hand, it is the generalization of the classical Kovalevskaya and Chaplygin cases. On the other hand, it is inscribed in the 6-parameter family of partiallyintegrable (under zero value of the area integral) Hamiltonian systems with two degrees of freedom. For the given problem, we study in details the critical subsystems — Hamiltonian systems with one degree of freedom which are restrictions of the initial system to the criticalset of the momentum mapping. We obtain an explicit parametrization of the critical set which gives the bifurcation diagram and the image of the momentum mapping. For all five critical subsystems we provide their explicit solutions in elliptic quadratures under constant value ofthe energy integral and the parameter of the problem. Besides that, for each critical subsystem we describe the bifurcations of the integral trajectories under the change of the energy level. It turns out that all non-trivial bifurcations of the saddle type are 2-atoms 𝐵 and 𝐶2 (standard transformations of two critical circles into one or two circles respectively).</p></trans-abstract><kwd-group xml:lang="ru"><kwd>интегрируемая система</kwd><kwd>критическая подсистема</kwd><kwd>бифуркационная диаграмма</kwd><kwd>решение в квадратурах</kwd><kwd>2-атом</kwd><kwd>молекула.</kwd></kwd-group><kwd-group xml:lang="en"><kwd>integrable system</kwd><kwd>critical subsystem</kwd><kwd>bifurcation diagram</kwd><kwd>solution in quadratures</kwd><kwd>2-atom</kwd><kwd>molecule.</kwd></kwd-group><funding-group><funding-statement xml:lang="ru">Исследование поддержано Российским научным фондом (проект 25-21-00086) и выполнено в Московском физико-техническом институте (национальном исследовательском университете).</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">Yehia H. M. New integrable problems in the dynamics of rigid bodies with the Kovalevskaya configuration: I. The case of axisymmetric forces // Mech. Res. Com. 1996. Vol. 23, №5. P. 423–427.</mixed-citation><mixed-citation xml:lang="en">Yehia, H. M. 1996, “New integrable problems in the dynamics of rigid bodies with the Kovalevskaya configuration: I. The case of axisymmetric forces”, Mech. Res. Com., vol. 23, no. 5, pp. 423–427.</mixed-citation></citation-alternatives></ref><ref id="cit2"><label>2</label><citation-alternatives><mixed-citation xml:lang="ru">Tsiganov A. V. On the Kowalevski-Goryachev-Chaplygin gyrostat // J. Phys. A: Math. Gen. 2002. Vol. 35, №22. P. L309–L318.</mixed-citation><mixed-citation xml:lang="en">Tsiganov, A. V. 2002, “On the Kowalevski-Goryachev-Chaplygin gyrostat”, J. Phys. A: Math. Gen., vol. 35, no. 22, pp. L309–L318.</mixed-citation></citation-alternatives></ref><ref id="cit3"><label>3</label><citation-alternatives><mixed-citation xml:lang="ru">Цыганов А. В. Разделение переменных в гиростате Ковалевской–Горячева–Чаплыгина // ТМФ. 2003. Том 135, №2. С. 240–247.</mixed-citation><mixed-citation xml:lang="en">Tsiganov, A. V. 2003, “Separation of Variables in the Kovalevskaya–Goryachev–Chaplygin Gyrostat”, Theoretical and Mathematical Physics, vol. 135, no. 2, pp. 651–658.</mixed-citation></citation-alternatives></ref><ref id="cit4"><label>4</label><citation-alternatives><mixed-citation xml:lang="ru">Yehia H. M. Comment on “On the Kowalevsky–Goryachev–Chaplygin gyrostat” // J. Phys. A: Math. Gen. 2002. Vol. 35, №49. P. 10669–10670.</mixed-citation><mixed-citation xml:lang="en">Yehia, H. M. 2002, “Comment on ‘On the Kowalevsky-Goryachev-Chaplygin gyrostat’ ”, J. Phys. A: Math. Gen., vol. 35, no. 49, pp. 10669–10670.</mixed-citation></citation-alternatives></ref><ref id="cit5"><label>5</label><citation-alternatives><mixed-citation xml:lang="ru">Kowalevski S. Sur le probl‘eme de la rotation d’un corps solide autour d’un point fixe // Acta Math. 1889. Vol. 12. P. 177–232.</mixed-citation><mixed-citation xml:lang="en">Kowalevski, S. 1889, “Sur le probl‘eme de la rotation d’un corps solide autour d’un point fixe”, Acta Math., vol. 12, pp. 177–232.</mixed-citation></citation-alternatives></ref><ref id="cit6"><label>6</label><citation-alternatives><mixed-citation xml:lang="ru">Харламов М. П. Бифуркации совместных уровней первых интегралов в случае Ковалевской // Прикл. матем. и механ. 1983. Том 47, №6. С. 922–930.</mixed-citation><mixed-citation xml:lang="en">Kharlamov, M.P. 1983, “Bifurcation of common levels of first integrals of the Kovalevskaya problem”, J. Appl. Math. Mech., vol. 47, no. 6, pp. 737–743.</mixed-citation></citation-alternatives></ref><ref id="cit7"><label>7</label><citation-alternatives><mixed-citation xml:lang="ru">Харламов М. П. Топологический анализ интегрируемых задач динамики твердого тела. Л.: Изд-во ЛГУ, 1988. 200 с.</mixed-citation><mixed-citation xml:lang="en">Kharlamov, M.P. 1988, “Topological analysis of integrable problems of rigid body dynamics”, Leningrad. Univ., Leningrad, 200 pp. (In Russian).</mixed-citation></citation-alternatives></ref><ref id="cit8"><label>8</label><citation-alternatives><mixed-citation xml:lang="ru">Болсинов А. В., Рихтер П., Фоменко А.Т. Метод круговых молекул и топология волчка Ковалевской // Матем. сб. 2000. Том 191, №2. С. 3–42.</mixed-citation><mixed-citation xml:lang="en">Bolsinov, A. V, Richter, P. H. &amp; Fomenko, A. T. 2000, “The method of loop molecules and the topology of the Kovalevskaya top”, Sb. Math., vol. 191, no. 2, pp. 151–188.</mixed-citation></citation-alternatives></ref><ref id="cit9"><label>9</label><citation-alternatives><mixed-citation xml:lang="ru">Харламов М.П. Топологический анализ и булевы функции: I. Методы и приложения к классическим системам // Нелинейная динам. 2010. Том 6, №4. С. 769–805.</mixed-citation><mixed-citation xml:lang="en">Kharlamov, M.P. 2010, “Topological analysis and Boolean functions. I. Methods and applications to classical systems”, Nelin. Dinam., vol. 6, no. 4, pp. 769–805. (In Russian).</mixed-citation></citation-alternatives></ref><ref id="cit10"><label>10</label><citation-alternatives><mixed-citation xml:lang="ru">Чаплыгин С. А. Новое частное решение задачи о движении твёрдого тела в жидкости // Тр. отд. физ. наук общ-ва любителей естествознания. 1903. Том 11, №2. С. 7–10.</mixed-citation><mixed-citation xml:lang="en">Chaplygin, S. A. 1903, “A new particular solution of the problem of motion of a rigid body in a fluid”, Tr. Otdel. Fiz. Nauk Obshch. Lubitelei Estestvozn., vol. 11, no. 2, pp. 7–10. (In Russian).</mixed-citation></citation-alternatives></ref><ref id="cit11"><label>11</label><citation-alternatives><mixed-citation xml:lang="ru">Ryabov P. E., Orel O. E. Bifurcation sets in a problem on motion of a rigid body in fluid and in the generalization of this problem // Regul. Chaotic Dyn. 1998. Vol. 3, №2. P. 82–91.</mixed-citation><mixed-citation xml:lang="en">Ryabov, P. E. &amp; Orel, O. E. 1998, “Bifurcation sets in a problem on motion of a rigid body in fluid and in the generalization of this problem”, Regul. Chaotic Dyn., vol. 3, no. 2, pp. 82–91.</mixed-citation></citation-alternatives></ref><ref id="cit12"><label>12</label><citation-alternatives><mixed-citation xml:lang="ru">Рябов П. Е. Фазовая топология задачи Чаплыгина о движении твёрдого тела в жидкости // Механика твёрдого тела. 2000. №30. С. 140–150.</mixed-citation><mixed-citation xml:lang="en">Ryabov, P. E. 2000, “Phase topology of the Chaplygin problem on the motion of a rigid body in a fluid”, Mekh. Tverd. Tela, no. 30, pp. 140–150. (In Russian).</mixed-citation></citation-alternatives></ref><ref id="cit13"><label>13</label><citation-alternatives><mixed-citation xml:lang="ru">Николаенко С. С. Топологическая классификация систем Чаплыгина в динамике твердого тела в жидкости // Матем. сб. 2014. Том 205, №2. С. 75–122.</mixed-citation><mixed-citation xml:lang="en">Nikolaenko, S. S. 2014, “A topological classification of the Chaplygin systems in the dynamics of a rigid body in a fluid”, Sb. Math., vol. 205, no. 2, pp. 224–268.</mixed-citation></citation-alternatives></ref><ref id="cit14"><label>14</label><citation-alternatives><mixed-citation xml:lang="ru">Fomenko A. T., Nikolaenko S. S. The Chaplygin case in dynamics of a rigid body in fluid is orbitally equivalent to the Euler case in rigid body dynamics and to the Jacobi problem about geodesics on the ellipsoid // J. Geom. Phys. 2015. Vol. 87. P. 115–133.</mixed-citation><mixed-citation xml:lang="en">Fomenko, A. T. &amp; Nikolaenko, S. S. 2015, “The Chaplygin case in dynamics of a rigid body in fluid is orbitally equivalent to the Euler case in rigid body dynamics and to the Jacobi problem about geodesics on the ellipsoid”, J. Geom. Phys., vol. 87, pp. 115–133.</mixed-citation></citation-alternatives></ref><ref id="cit15"><label>15</label><citation-alternatives><mixed-citation xml:lang="ru">Ryabov P. E. Bifurcation sets in an integrable problem on motion of a rigid body in fluid // Regul. Chaotic Dyn. 1999. Vol. 4, №4. P. 59–76.</mixed-citation><mixed-citation xml:lang="en">Ryabov, P. E. 1999, “Bifurcation sets in an integrable problem on motion of a rigid body in fluid”, Regul. Chaotic Dyn., vol. 4, no. 4, pp. 59–76.</mixed-citation></citation-alternatives></ref><ref id="cit16"><label>16</label><citation-alternatives><mixed-citation xml:lang="ru">Ryabov P. E., Orel O.E. Topology, bifurcations and Liouville classification of Kirchhoff equations with an additional integral of fourth degree // J. Phys. A: Math. Gen. 2001. Vol. 34, №11. P. 2149–2163.</mixed-citation><mixed-citation xml:lang="en">Ryabov, P. E. &amp; Orel, O. E. 2001, “Topology, bifurcations and Liouville classification of Kirchhoff equations with an additional integral of fourth degree”, J. Phys. A: Math. Gen., vol. 34, no. 11, pp. 2149–2163.</mixed-citation></citation-alternatives></ref><ref id="cit17"><label>17</label><citation-alternatives><mixed-citation xml:lang="ru">Болсинов А. В., Фоменко А.Т. Интегрируемые гамильтоновы системы. Геометрия, топология, классификация. В 2 т. Ижевск: Изд. дом “Удмуртский университет”, 1999. 444 с., 447 с.</mixed-citation><mixed-citation xml:lang="en">Bolsinov, A. V. &amp; Fomenko, A. T. 2004, “Integrable Hamiltonian systems. Geometry, topology, classification”, Chapman &amp; Hall/CRC, Boca Raton, FL, 730 pp.</mixed-citation></citation-alternatives></ref></ref-list><fn-group><fn fn-type="conflict"><p>The authors declare that there are no conflicts of interest present.</p></fn></fn-group></back></article>
