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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">10.22405/2226-8383-2025-26-2-125-140</article-id><article-id custom-type="elpub" pub-id-type="custom">cheb-1964</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>Бифуркации магнитных геодезических потоков на торических поверхностях вращения</article-title><trans-title-group xml:lang="en"><trans-title>Bifurcations of magnetic geodesic flows on toric surfaces of revolution</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>Кобцев</surname><given-names>Иван Федорович</given-names></name><name name-style="western" xml:lang="en"><surname>Kobtsev</surname><given-names>Ivan Fedorovich</given-names></name></name-alternatives><email xlink:type="simple">int396.kobtsev@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>Кудрявцева</surname><given-names>Елена Александровна</given-names></name><name name-style="western" xml:lang="en"><surname>Kudryavtseva</surname><given-names>Elena Alexandrovna</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">eakudr@mech.math.msu.su</email><xref ref-type="aff" rid="aff-2"/></contrib></contrib-group><aff-alternatives id="aff-1"><aff xml:lang="ru"><institution>Московский государственный технический университет им. Н.Э. Баумана</institution><country>Россия</country></aff><aff xml:lang="en"><institution>Bauman Moscow State Technical University</institution><country>Russian Federation</country></aff></aff-alternatives><aff-alternatives id="aff-2"><aff xml:lang="ru"><institution>Московский государственный университет им. 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 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>125</fpage><lpage>140</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Кобцев И.Ф., Кудрявцева Е.А., 2025</copyright-statement><copyright-year>2025</copyright-year><copyright-holder xml:lang="ru">Кобцев И.Ф., Кудрявцева Е.А.</copyright-holder><copyright-holder xml:lang="en">Kobtsev I.F., Kudryavtseva E.A.</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/1964">https://www.chebsbornik.ru/jour/article/view/1964</self-uri><abstract><p>Изучаются магнитные геодезические потоки, инвариантные относительно вращений, на двумерном торе. Предполагается, что пара 2𝜋-периодических функций (𝑓, Λ), задающая динамическую систему, удовлетворяет условиям общего положения, при этом функция Λ, задающая магнитное поле, принимает значения в окружности, если магнитное поле не является точным. Описана топология слоения Лиувилля данной интегрируемой системы вблизи ее особых орбит и особых слоев, найдены типы этих особенностей. Описана топология слоения Лиувилля на неособых трехмерных изоэнергетических многообразиях путем вычисления инварианта Фоменко – Цишанга. Показано, что слоения Лиувиллядля геодезического потока и для неточного магнитного геодезического потока на любом изоэнергетическом многообразии имеют разную топологию. Описаны все возможные бифуркационные диаграммы отображений момента таких интегрируемых систем.</p></abstract><trans-abstract xml:lang="en"><p>We study magnetic geodesic flows invariant under rotations on the 2-torus. The dynamical system is given by a generic pair of 2𝜋-periodic functions (𝑓, Λ), where the function Λ takes values in a circle if the magnetic field is not exact. Topology of the Liouville fibration ofthe given integrable system near its singular orbits and singular fibers is decribed. Types of these singularities are computed. Topology of the Liouville fibration on regular 3-dimensional isoenergy manifolds is described by computing the Fomenko-Zieschang invariant. It is shown that Liouville fibrations for geodesic flow and non-exact magnetic geodesic flow on any isoenergy manifold have different topology. All possible bifurcation diagrams of the momentum maps of such integrable systems are described.</p></trans-abstract><kwd-group xml:lang="ru"><kwd>точный магнитный геодезический поток</kwd><kwd>интегрируемая система</kwd><kwd>топология слоения Лиувилля</kwd><kwd>бифуркационная диаграмма.</kwd></kwd-group><kwd-group xml:lang="en"><kwd>exact magnetic geodesic flow</kwd><kwd>integrable system</kwd><kwd>topology of the Liouville fibration</kwd><kwd>bifurcation diagram.</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">Болсинов А. В., Фоменко А.Т. Интегрируемые гамильтоновы системы. Геометрия, топо-</mixed-citation><mixed-citation xml:lang="en">Bolsinov, A. V. &amp; Fomenko, A. T. 2004, Integrable Hamiltonian systems: geometry, topology,</mixed-citation></citation-alternatives></ref><ref id="cit2"><label>2</label><citation-alternatives><mixed-citation xml:lang="ru">логия, классификация. — Ижевск: Издательский дом «Удмуртский университет», 1999.</mixed-citation><mixed-citation xml:lang="en">classification, Chapman &amp; Hall /CRC, Boca Raton, London, N.Y., Washington.</mixed-citation></citation-alternatives></ref><ref id="cit3"><label>3</label><citation-alternatives><mixed-citation xml:lang="ru">Кантонистова Е. О. Топологическая классификация интегрируемых гамильтоновых си-</mixed-citation><mixed-citation xml:lang="en">Kantonistova, E. O. 2016, “Topological classification of integrable Hamiltonian systems in a</mixed-citation></citation-alternatives></ref><ref id="cit4"><label>4</label><citation-alternatives><mixed-citation xml:lang="ru">стем на поверхностях вращения в потенциальном поле // Матем. сб. 2016. Т. 207, №3.</mixed-citation><mixed-citation xml:lang="en">potential field on surfaces of revolution”, Sb. Math., vol. 207, no. 3, pp. 358–399.</mixed-citation></citation-alternatives></ref><ref id="cit5"><label>5</label><citation-alternatives><mixed-citation xml:lang="ru">С. 47–92.</mixed-citation><mixed-citation xml:lang="en">Timonina, D. S. 2018, “Liouville classification of integrable geodesic flows in a potential field on</mixed-citation></citation-alternatives></ref><ref id="cit6"><label>6</label><citation-alternatives><mixed-citation xml:lang="ru">Тимонина Д. С. Лиувиллева классификация интегрируемых геодезических потоков в по-</mixed-citation><mixed-citation xml:lang="en">two-dimensional manifolds of revolution: the torus and the Klein bottle”, Sb. Math., vol. 209,</mixed-citation></citation-alternatives></ref><ref id="cit7"><label>7</label><citation-alternatives><mixed-citation xml:lang="ru">тенциальном поле на двумерных многообразиях вращения: торе и бутылке Клейна //</mixed-citation><mixed-citation xml:lang="en">no. 11, pp. 1644–1676.</mixed-citation></citation-alternatives></ref><ref id="cit8"><label>8</label><citation-alternatives><mixed-citation xml:lang="ru">Матем. сб. 2018. Т. 209, №11. С. 103–136.</mixed-citation><mixed-citation xml:lang="en">Antonov, E. I. &amp; Kozlov, I. K. 2020, “Liouville classification of integrable geodesic flows on a</mixed-citation></citation-alternatives></ref><ref id="cit9"><label>9</label><citation-alternatives><mixed-citation xml:lang="ru">Антонов Е. И., Козлов И. К. Лиувиллева классификация интегрируемых геодезических</mixed-citation><mixed-citation xml:lang="en">projective plane in potential field”, Chebyshevskii sbornik, vol. 21, no. 2, pp. 10–25.</mixed-citation></citation-alternatives></ref><ref id="cit10"><label>10</label><citation-alternatives><mixed-citation xml:lang="ru">потоков на проективной плоскости в потенциальном поле // Чебышевский сборник. 2020.</mixed-citation><mixed-citation xml:lang="en">Kozlov, I. &amp; Oshemkov, A. 2017, “Integrable systems with linear periodic integral for the Lie</mixed-citation></citation-alternatives></ref><ref id="cit11"><label>11</label><citation-alternatives><mixed-citation xml:lang="ru">Т. 21, №2. С. 10–25.</mixed-citation><mixed-citation xml:lang="en">algebra 𝑒(3)”, Lobachevskii J. Math., vol. 38, pp. 1014–1026. https://doi.org/10.1134/</mixed-citation></citation-alternatives></ref><ref id="cit12"><label>12</label><citation-alternatives><mixed-citation xml:lang="ru">Kozlov I., Oshemkov A. Integrable systems with linear periodic integral for the Lie algebra 𝑒(3)</mixed-citation><mixed-citation xml:lang="en">S1995080217060063</mixed-citation></citation-alternatives></ref><ref id="cit13"><label>13</label><citation-alternatives><mixed-citation xml:lang="ru">// Lobachevskii J. Math. 2017. Vol. 38. P. 1014–1026.</mixed-citation><mixed-citation xml:lang="en">Kudryavtseva, E. A. &amp; Oshemkov, A. A. 2020, “Bifurcations of integrable mechanival systems</mixed-citation></citation-alternatives></ref><ref id="cit14"><label>14</label><citation-alternatives><mixed-citation xml:lang="ru">Кудрявцева Е. А., Ошемков А. А. Бифуркации интегрируемых механических систем с маг-</mixed-citation><mixed-citation xml:lang="en">with magnetic field on surfaces of revolution”, Chebyshevskii sbornik, vol. 21, no. 2, pp. 244–265.</mixed-citation></citation-alternatives></ref><ref id="cit15"><label>15</label><citation-alternatives><mixed-citation xml:lang="ru">нитным полем на поверхностях вращения // Чебышевский сборник. 2020. Т. 21, №2. С. 244–</mixed-citation><mixed-citation xml:lang="en">Fomenko, A. T. 1987, “The topology of surfaces of constant energy in integrable Hamiltonian</mixed-citation></citation-alternatives></ref><ref id="cit16"><label>16</label><citation-alternatives><mixed-citation xml:lang="ru">systems, and obstructions to integrability”, Math. USSR-Izv., vol. 29, no. 3, pp. 629–658.</mixed-citation><mixed-citation xml:lang="en">systems, and obstructions to integrability”, Math. USSR-Izv., vol. 29, no. 3, pp. 629–658.</mixed-citation></citation-alternatives></ref><ref id="cit17"><label>17</label><citation-alternatives><mixed-citation xml:lang="ru">Фоменко А.Т. Топология поверхностей постоянной энергии интегрируемых гамильтоно-</mixed-citation><mixed-citation xml:lang="en">Fomenko, A. T. 1986. “Morse theory of integrable Hamiltonian systems”, Soviet Math. Dokl.,</mixed-citation></citation-alternatives></ref><ref id="cit18"><label>18</label><citation-alternatives><mixed-citation xml:lang="ru">вых систем и препятствия к интегрируемости // Изв. АН СССР. Серия матем. 1986. Т. 50,</mixed-citation><mixed-citation xml:lang="en">vol. 33, no. 2, pp. 502–506.</mixed-citation></citation-alternatives></ref><ref id="cit19"><label>19</label><citation-alternatives><mixed-citation xml:lang="ru">№6. С. 1276–1307.</mixed-citation><mixed-citation xml:lang="en">Kobtsev, I. F. &amp; Kudryavtseva, E. A. 2024, “Bifurcations of magnetic geodesic flows on surfaces</mixed-citation></citation-alternatives></ref><ref id="cit20"><label>20</label><citation-alternatives><mixed-citation xml:lang="ru">Фоменко А.Т. Теория Морса интегрируемых гамильтоновых систем // Доклады АН</mixed-citation><mixed-citation xml:lang="en">of revolution”, Russian Journal of Mathematical Physics (in print).</mixed-citation></citation-alternatives></ref><ref id="cit21"><label>21</label><citation-alternatives><mixed-citation xml:lang="ru">СССР. 1986. Т. 287, №5. С. 1071–1075.</mixed-citation><mixed-citation xml:lang="en">Fomenko, A. T. &amp; Zieschang, H. 1987, “On the topology of the three-dimensional manifolds</mixed-citation></citation-alternatives></ref><ref id="cit22"><label>22</label><citation-alternatives><mixed-citation xml:lang="ru">Kobtsev I. F., Kudryavtseva E. A. Bifurcations of magnetic geodesic flows on surfaces of</mixed-citation><mixed-citation xml:lang="en">arising in Hamiltonian mechanics”, Soviet Math. Dokl., vol. 35, no. 2, pp. 520–534.</mixed-citation></citation-alternatives></ref><ref id="cit23"><label>23</label><citation-alternatives><mixed-citation xml:lang="ru">revolution // Russian Journal of Mathematical Physics (in print).</mixed-citation><mixed-citation xml:lang="en">Fomenko, A. T. 1988, “Topological invariants of Liouville integrable Hamiltonian systems”,</mixed-citation></citation-alternatives></ref><ref id="cit24"><label>24</label><citation-alternatives><mixed-citation xml:lang="ru">Фоменко А.Т., Цишанг Х. О топологии трехмерных многообразий, возникающих в га-</mixed-citation><mixed-citation xml:lang="en">Funct. Anal. Appl., vol. 22, no. 4, pp. 286–296.</mixed-citation></citation-alternatives></ref><ref id="cit25"><label>25</label><citation-alternatives><mixed-citation xml:lang="ru">мильтоновой механике // Доклады АН СССР. 1987. Т. 294, №2. С. 283–287.</mixed-citation><mixed-citation xml:lang="en">Fomenko, A. T. &amp; Zieschang, H. 1991, “A topological invariant and a criterion for the equivalence</mixed-citation></citation-alternatives></ref><ref id="cit26"><label>26</label><citation-alternatives><mixed-citation xml:lang="ru">Фоменко А.Т. Топологические инварианты гамильтоновых систем, интегрируемых по Ли-</mixed-citation><mixed-citation xml:lang="en">of integrable Hamiltonian systems with two degrees of freedom”, Math.USSR Izv., vol. 36, no. 3,</mixed-citation></citation-alternatives></ref><ref id="cit27"><label>27</label><citation-alternatives><mixed-citation xml:lang="ru">увиллю // Функц. анализ и его прил. 1988. Т. 22, №4. С. 38–51.</mixed-citation><mixed-citation xml:lang="en">pp. 567–596.</mixed-citation></citation-alternatives></ref><ref id="cit28"><label>28</label><citation-alternatives><mixed-citation xml:lang="ru">Фоменко А.Т., Цишанг Х. Топологический инвариант и критерий эквивалентности инте-</mixed-citation><mixed-citation xml:lang="en">Vedyushkina, V. V. &amp; Pustovoitov, S. E. 2023, “Classification of Liouville foliations of integrable</mixed-citation></citation-alternatives></ref><ref id="cit29"><label>29</label><citation-alternatives><mixed-citation xml:lang="ru">грируемых гамильтоновых систем с двумя степенями свободы // Изв. АН СССР. 1990.</mixed-citation><mixed-citation xml:lang="en">topological billiards in magnetic fields”, Sb. Math., vol. 214, no. 2, pp. 166–196.</mixed-citation></citation-alternatives></ref><ref id="cit30"><label>30</label><citation-alternatives><mixed-citation xml:lang="ru">Т. 54, №3. С. 546–575.</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</mixed-citation></citation-alternatives></ref><ref id="cit31"><label>31</label><citation-alternatives><mixed-citation xml:lang="ru">Ведюшкина В. В., Пустовойтов С. Е. Классификация слоений Лиувилля интегрируемых</mixed-citation><mixed-citation xml:lang="en">topology of the Kovalevskaya top”, Sb. Math., vol. 191, no. 2, pp. 151–188.</mixed-citation></citation-alternatives></ref><ref id="cit32"><label>32</label><citation-alternatives><mixed-citation xml:lang="ru">топологических биллиардов в магнитном поле // Матем. сб. 2023. Т. 214, №2. С. 23–57.</mixed-citation><mixed-citation xml:lang="en">Efstathiou, K. &amp; Giacobbe, A. 2012, “The topology associated with cusp singular points”,</mixed-citation></citation-alternatives></ref><ref id="cit33"><label>33</label><citation-alternatives><mixed-citation xml:lang="ru">Болсинов А. В., Рихтер П., Фоменко А.Т. Метод круговых молекул и топология волчка</mixed-citation><mixed-citation xml:lang="en">Nonlinearity, vol. 25, pp. 3409–3422.</mixed-citation></citation-alternatives></ref><ref id="cit34"><label>34</label><citation-alternatives><mixed-citation xml:lang="ru">Ковалевской // Матем. сб. 2000. Т. 191, №2. С. 3–42.</mixed-citation><mixed-citation xml:lang="en">Bolsinov, A. V., Guglielmi, L. &amp; Kudryavtseva, E. A. 2018, “Symplectic invariants for parabolic</mixed-citation></citation-alternatives></ref><ref id="cit35"><label>35</label><citation-alternatives><mixed-citation xml:lang="ru">Efstathiou K., Giacobbe A. The topology associated with cusp singular points // Nonlinearity.</mixed-citation><mixed-citation xml:lang="en">orbits and cusp singularities of integrable systems with two degrees of freedom”, Philosophical</mixed-citation></citation-alternatives></ref><ref id="cit36"><label>36</label><citation-alternatives><mixed-citation xml:lang="ru">V. 25. P. 3409–3422.</mixed-citation><mixed-citation xml:lang="en">Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 376,</mixed-citation></citation-alternatives></ref><ref id="cit37"><label>37</label><citation-alternatives><mixed-citation xml:lang="ru">Bolsinov A. V., Guglielmi L., Kudryavtseva E. A. Symplectic invariants for parabolic orbits</mixed-citation><mixed-citation xml:lang="en">no. 2131, 20170424.</mixed-citation></citation-alternatives></ref><ref id="cit38"><label>38</label><citation-alternatives><mixed-citation xml:lang="ru">and cusp singularities of integrable systems with two degrees of freedom // Philosophical</mixed-citation><mixed-citation xml:lang="en">Lerman, L. M. &amp; Umanskii, Ya. L. 1987, “The structure of a Poisson action of 𝑅2 on a fourdimensional</mixed-citation></citation-alternatives></ref><ref id="cit39"><label>39</label><citation-alternatives><mixed-citation xml:lang="ru">Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 2018.</mixed-citation><mixed-citation xml:lang="en">symplectic manifold. I”, Selecta Math. Sov. (transl. from Russian preprint of 1981),</mixed-citation></citation-alternatives></ref><ref id="cit40"><label>40</label><citation-alternatives><mixed-citation xml:lang="ru">V. 376, №2131. 20170424.</mixed-citation><mixed-citation xml:lang="en">vol. 6, pp. 365–396.</mixed-citation></citation-alternatives></ref><ref id="cit41"><label>41</label><citation-alternatives><mixed-citation xml:lang="ru">Lerman L. M., Umanskii Ya. L. The structure of a Poisson action of 𝑅2 on a four-dimensional</mixed-citation><mixed-citation xml:lang="en">Lerman, L. M. &amp; Umanskii, Ya. L. 1994, “Classification of four-dimensional integrable Hamiltonian</mixed-citation></citation-alternatives></ref><ref id="cit42"><label>42</label><citation-alternatives><mixed-citation xml:lang="ru">symplectic manifold. I // Selecta Math. Sov. 1987 (transl. from Russian preprint of 1981). V. 6.</mixed-citation><mixed-citation xml:lang="en">systems and Poisson actions of 𝑅2 in extended neighborhoods of simple singular points.</mixed-citation></citation-alternatives></ref><ref id="cit43"><label>43</label><citation-alternatives><mixed-citation xml:lang="ru">P. 365–396.</mixed-citation><mixed-citation xml:lang="en">I”, Russian Acad. Sci. Sb. Math., vol. 77, no. 2, pp. 511–542.</mixed-citation></citation-alternatives></ref><ref id="cit44"><label>44</label><citation-alternatives><mixed-citation xml:lang="ru">Lerman L. M., Umanskii Ya. L. Classification of four-dimensional integrable Hamiltonian</mixed-citation><mixed-citation xml:lang="en">Kudryavtseva, E. &amp; Martynchuk, N. 2021, “Existence of a smooth Hamiltonian circle action near</mixed-citation></citation-alternatives></ref><ref id="cit45"><label>45</label><citation-alternatives><mixed-citation xml:lang="ru">systems and Poisson actions of 𝑅2 in extended neighborhoods of simple singular points. I</mixed-citation><mixed-citation xml:lang="en">parabolic orbits and cuspidal tori”, Regular and Chaotic Dynamics, vol. 26, no. 6, pp. 732–741.</mixed-citation></citation-alternatives></ref><ref id="cit46"><label>46</label><citation-alternatives><mixed-citation xml:lang="ru">// Russian Acad. Sci. Sb. Math. 1994. V. 77, №2. P. 511–542.</mixed-citation><mixed-citation xml:lang="en">Kudryavtseva, E. A. 2022, “Hidden toric symmetry and structural stability of singularities in</mixed-citation></citation-alternatives></ref><ref id="cit47"><label>47</label><citation-alternatives><mixed-citation xml:lang="ru">Kudryavtseva E., Martynchuk N. Existence of a smooth Hamiltonian circle action near parabolic</mixed-citation><mixed-citation xml:lang="en">integrable systems”, Europ. J. Math., vol. 8, pp. 1487–1549.</mixed-citation></citation-alternatives></ref><ref id="cit48"><label>48</label><citation-alternatives><mixed-citation xml:lang="ru">orbits and cuspidal tori // Regular and Chaotic Dynamics. 2021. V. 26, №6. P. 732–741.</mixed-citation><mixed-citation xml:lang="en">orbits and cuspidal tori // Regular and Chaotic Dynamics. 2021. V. 26, №6. P. 732–741.</mixed-citation></citation-alternatives></ref><ref id="cit49"><label>49</label><citation-alternatives><mixed-citation xml:lang="ru">Kudryavtseva E. A. Hidden toric symmetry and structural stability of singularities in integrable</mixed-citation><mixed-citation xml:lang="en">Kudryavtseva E. A. Hidden toric symmetry and structural stability of singularities in integrable</mixed-citation></citation-alternatives></ref><ref id="cit50"><label>50</label><citation-alternatives><mixed-citation xml:lang="ru">systems // Europ. J. Math. 2022. V. 8. P. 1487–1549.</mixed-citation><mixed-citation xml:lang="en">systems // Europ. J. Math. 2022. V. 8. P. 1487–1549.</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>
