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<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">Discrete and Continuous Models and Applied Computational Science</journal-id><journal-title-group><journal-title xml:lang="en">Discrete and Continuous Models and Applied Computational Science</journal-title><trans-title-group xml:lang="ru"><trans-title>Discrete and Continuous Models and Applied Computational Science</trans-title></trans-title-group></journal-title-group><issn publication-format="print">2658-4670</issn><issn publication-format="electronic">2658-7149</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">51928</article-id><article-id pub-id-type="doi">10.22363/2658-4670-2026-34-2-274-278</article-id><article-id pub-id-type="edn">JOTBVJ</article-id><article-categories><subj-group subj-group-type="toc-heading" xml:lang="en"><subject>Letters</subject></subj-group><subj-group subj-group-type="toc-heading" xml:lang="ru"><subject>Письма</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">On the classical Volterra spectral equation</article-title><trans-title-group xml:lang="ru"><trans-title>О классическом спектральном уравнении Вольтерры</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-4053-7983</contrib-id><name-alternatives><name xml:lang="en"><surname>Tsedenbayar</surname><given-names>Dashdondog</given-names></name><name xml:lang="ru"><surname>Цэдэнбаяр</surname><given-names>Д.</given-names></name></name-alternatives><bio xml:lang="en"><p>Academician, Professor, Doctor of Sciences in Physics and Mathematics</p></bio><email>tsdnbr@must.edu.mn</email><xref ref-type="aff" rid="aff1"/><xref ref-type="aff" rid="aff2"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="scopus">36661503100</contrib-id><name-alternatives><name xml:lang="en"><surname>Ser-Od</surname><given-names>Bayaraa</given-names></name><name xml:lang="ru"><surname>Сэр-Од</surname><given-names>Б.</given-names></name></name-alternatives><bio xml:lang="en"><p>Associate professor of Department of Mathematics at School of Applied Sciences, Mongolian University of Science and Technology</p></bio><email>serod_b@must.edu.mn</email><xref ref-type="aff" rid="aff2"/></contrib><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Wuren</surname><given-names>Qiqige</given-names></name><name xml:lang="ru"><surname>Цэцэг</surname><given-names>У.</given-names></name></name-alternatives><bio xml:lang="en">College of Mathematics and Computer Science, Chifeng University,  No. 1, Yingbin Road, Hongshan District, Chinfeng city, Chifeng-024000, Inner Mongolia, China</bio><email>wurenqiqige@126.com</email><xref ref-type="aff" rid="aff3"/></contrib></contrib-group><aff-alternatives id="aff1"><aff><institution xml:lang="en">Institute of Mathematics and Digital Technology, Mongolian Academy of Sciences</institution></aff><aff><institution xml:lang="ru">Институт математики и цифровой технологии, Монгольская Академия Наук</institution></aff></aff-alternatives><aff-alternatives id="aff2"><aff><institution xml:lang="en">Mongolian University of Science and Technology</institution></aff><aff><institution xml:lang="ru">Монгольский Государственный Университет Науки и Технологии</institution></aff></aff-alternatives><aff-alternatives id="aff3"><aff><institution xml:lang="en">College of Mathematics and Computer Science, Chifeng University</institution></aff><aff><institution xml:lang="ru">Колледж математики и информатики Университета Чифэн</institution></aff></aff-alternatives><pub-date date-type="pub" iso-8601-date="2026-08-15" publication-format="electronic"><day>15</day><month>08</month><year>2026</year></pub-date><volume>34</volume><issue>2</issue><issue-title xml:lang="en">VOL 34, NO2 (2026)</issue-title><issue-title xml:lang="ru">ТОМ 34, №2 (2026)</issue-title><fpage>274</fpage><lpage>278</lpage><history><date date-type="received" iso-8601-date="2026-08-20"><day>20</day><month>08</month><year>2026</year></date></history><permissions><copyright-statement xml:lang="en">Copyright ©; 2026, Tsedenbayar D., Ser-Od B., Wuren Q.</copyright-statement><copyright-statement xml:lang="ru">Copyright ©; 2026, Цэдэнбаяр Д., Сэр-Од Б., Цэцэг У.</copyright-statement><copyright-year>2026</copyright-year><copyright-holder xml:lang="en">Tsedenbayar D., Ser-Od B., Wuren Q.</copyright-holder><copyright-holder xml:lang="ru">Цэдэнбаяр Д., Сэр-Од Б., Цэцэг У.</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/4.0</ali:license_ref></license></permissions><self-uri xlink:href="https://journals.rudn.ru/miph/article/view/51928">https://journals.rudn.ru/miph/article/view/51928</self-uri><abstract xml:lang="en"><p>We study the characterizations of the classical Volterra operator based on a simple relation between its singular numbers and the eigenvalues of its imaginary part on <span class="math">\( L^2[0,1] \)</span>.</p></abstract><trans-abstract xml:lang="ru"><p>Мы изучаем характеристики классического оператора Вольтерры на основе простого соотношения между его сингулярными числами и собственными значениями его мнимой части на <span class="math">\( L^2[0,1] \)</span>.</p></trans-abstract><kwd-group xml:lang="en"><kwd>Volterra operator</kwd><kwd>trace operator</kwd><kwd>operator norm</kwd><kwd>eigenvalue</kwd></kwd-group><kwd-group xml:lang="ru"><kwd>Оператор Вольтерры</kwd><kwd>оператор следа</kwd><kwd>норма оператора</kwd><kwd>собственное значение</kwd></kwd-group><funding-group><award-group><funding-source><institution-wrap><institution xml:lang="en">Wuren Qiqige’s research was supported by a grant from the Doctoral Research and Innovation Development Fund of Chifeng University (Project Number: BSJJ077)</institution></institution-wrap></funding-source></award-group></funding-group></article-meta><fn-group/></front><body></body><back><ref-list><ref id="B1"><label>1.</label><mixed-citation>I. 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