<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE root>
<article 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" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" article-type="research-article" dtd-version="1.2" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">Contemporary Mathematics. Fundamental Directions</journal-id><journal-title-group><journal-title xml:lang="en">Contemporary Mathematics. Fundamental Directions</journal-title><trans-title-group xml:lang="ru"><trans-title>Современная математика. Фундаментальные направления</trans-title></trans-title-group></journal-title-group><issn publication-format="print">2413-3639</issn><issn publication-format="electronic">2949-0618</issn><publisher><publisher-name xml:lang="en">Peoples’ Friendship University of Russia named after Patrice Lumumba (RUDN University)</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">28872</article-id><article-id pub-id-type="doi">10.22363/2413-3639-2021-67-2-408-421</article-id><article-categories><subj-group subj-group-type="toc-heading" xml:lang="en"><subject>Articles</subject></subj-group><subj-group subj-group-type="toc-heading" xml:lang="ru"><subject>Статьи</subject></subj-group><subj-group subj-group-type="article-type"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title xml:lang="en">Direct and Inverse Problems of Spectral Analysis for Arbitrary-Order Differential Operators with Nonintegrable Regular Singularities</article-title><trans-title-group xml:lang="ru"><trans-title>Прямые и обратные задачи спектрального анализа для дифференциальных операторов произвольных порядков с неинтегрируемыми регулярными особенностями</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Yurko</surname><given-names>V. A.</given-names></name><name xml:lang="ru"><surname>Юрко</surname><given-names>Вячеслав A.</given-names></name></name-alternatives><email>yurkova@info.sgu.ru</email><xref ref-type="aff" rid="aff1"/></contrib></contrib-group><aff-alternatives id="aff1"><aff><institution xml:lang="en">Chernyshevskii Saratov National Research State University</institution></aff><aff><institution xml:lang="ru">Саратовский национальный исследовательский государственный университет им. Н. Г. Чернышевского</institution></aff></aff-alternatives><pub-date date-type="pub" iso-8601-date="2021-12-15" publication-format="electronic"><day>15</day><month>12</month><year>2021</year></pub-date><volume>67</volume><issue>2</issue><issue-title xml:lang="en">Dedicated to the memory of Professor N. D. Kopachevsky</issue-title><issue-title xml:lang="ru">Посвящается памяти профессора Н. Д. Копачевского</issue-title><fpage>408</fpage><lpage>421</lpage><history><date date-type="received" iso-8601-date="2021-10-23"><day>23</day><month>10</month><year>2021</year></date></history><permissions><copyright-statement xml:lang="en">Copyright ©; 2021, Contemporary Mathematics. Fundamental Directions</copyright-statement><copyright-statement xml:lang="ru">Copyright ©; 2021, Современная математика. Фундаментальные направления</copyright-statement><copyright-year>2021</copyright-year><copyright-holder xml:lang="en">Contemporary Mathematics. Fundamental Directions</copyright-holder><copyright-holder xml:lang="ru">Современная математика. Фундаментальные направления</copyright-holder><ali:free_to_read xmlns:ali="http://www.niso.org/schemas/ali/1.0/"/><license><ali:license_ref xmlns:ali="http://www.niso.org/schemas/ali/1.0/">https://creativecommons.org/licenses/by-nc-nd/4.0/deed.en</ali:license_ref></license></permissions><self-uri xlink:href="https://journals.rudn.ru/CMFD/article/view/28872">https://journals.rudn.ru/CMFD/article/view/28872</self-uri><abstract xml:lang="en"><p style="text-align: justify;">A short review is presented of results on the spectral theory of arbitrary order ordinary differential operators with non-integrable regular singularities. We establish properties of spectral characteristics, prove theorems on completeness of root functions in the corresponding spaces, prove expansion and equiconvergence theorems, and provide a solution of the inverse spectral problem for this class of operators.</p></abstract><trans-abstract xml:lang="ru"><p style="text-align: justify;">Дается краткий обзор результатов по спектральной теории обыкновенных дифференциальных операторов произвольных порядков с неинтегрируемыми регулярными особенностями. Установлены свойства спектральных характеристик, доказаны теоремы о полноте корневых функций в соответствующих пространствах, теоремы о разложении и равносходимости, приводится решение обратной спектральной задачи для этого класса операторов.</p></trans-abstract><funding-group/></article-meta></front><body></body><back><ref-list><ref id="B1"><label>1.</label><mixed-citation>Вазов В. Асимптотические разложения решений обыкновенных дифференциальных уравнений. - М.: Мир, 1968.</mixed-citation></ref><ref id="B2"><label>2.</label><mixed-citation>Костюченко А. Г., Саргсян И. С. Распределение собственных значений. Самосопряженные обыкновенные дифференциальные операторы. - М.: Наука, 1979.</mixed-citation></ref><ref id="B3"><label>3.</label><mixed-citation>Наймарк М. А. Линейные дифференциальные операторы. - М.: Наука, 1969.</mixed-citation></ref><ref id="B4"><label>4.</label><mixed-citation>Юрко В. А. О дифференциальных операторах высших порядков с регулярной особенностью// Мат. сб. - 1995. - 186, № 6. - С. 133-160.</mixed-citation></ref><ref id="B5"><label>5.</label><mixed-citation>Юрко В. А. Введение в теорию обратных спектральных задач. - М.: Физматлит, 2007.</mixed-citation></ref><ref id="B6"><label>6.</label><mixed-citation>Ignatiev M. Yu. Integral transforms connected with differential systems with a singularity// Tamkang J. Math. - 2019. - 50, № 3. - С. 253-268.</mixed-citation></ref><ref id="B7"><label>7.</label><mixed-citation>Ignatiev M. Yu. Asymptotics of solutions of some integral equations connected with differential systems with a singularity// Изв. Саратов. ун-та. Нов. сер. Сер. Мат. Мех. Инф. - 2020. - 20, № 1. - С. 17-28.</mixed-citation></ref><ref id="B8"><label>8.</label><mixed-citation>Turrittin H. Stokes multipliers for asymptotic solutions of a certain differential equation// Trans. Am. Math. Soc. - 1950. - 68. - С. 304-329.</mixed-citation></ref><ref id="B9"><label>9.</label><mixed-citation>Yurko V. A. On higher-order differential operators with a singular point// Inverse Problems. - 1993. - 9, № 4. - С. 495-502.</mixed-citation></ref><ref id="B10"><label>10.</label><mixed-citation>Yurko V. A. Inverse spectral problems for differential operators and their applications. - Amsterdam: Gordon and Breach Sci. Publ., 2000.</mixed-citation></ref><ref id="B11"><label>11.</label><mixed-citation>Yurko V. A. Higher-order differential equations having a singularity in an interior point// Results Math. - 2002. - 42, № 1-2. - С. 177-191.</mixed-citation></ref><ref id="B12"><label>12.</label><mixed-citation>Yurko V. A. Integral transforms connected with higher-order differential operators with a singularity// Integral Transforms Spec. Funct. - 2002. - 13, № 6. - С. 497-511.</mixed-citation></ref></ref-list></back></article>
