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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">10.22405/2226-8383-2022-23-5-72-86</article-id><article-id custom-type="elpub" pub-id-type="custom">cheb-1408</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>Проблема Ферма — Торричелли в случае трёх точек в нормированных плоскостях</article-title><trans-title-group xml:lang="en"><trans-title>The Fermat–Torricelli problem in the case of three-point sets in normed planes</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>Илюхин</surname><given-names>Даниил Александрович</given-names></name><name name-style="western" xml:lang="en"><surname>Ilyukhin</surname><given-names>Daniil Alexandrovich</given-names></name></name-alternatives><bio xml:lang="ru"><p>студент</p></bio><bio xml:lang="en"><p>student</p></bio><email xlink:type="simple">daniil.ilukhin@math.msu.ru</email><xref ref-type="aff" rid="aff-1"/></contrib></contrib-group><aff-alternatives id="aff-1"><aff xml:lang="ru"><institution>Московский государственный университет им. М. В. Ломоносова</institution><country>Россия</country></aff><aff xml:lang="en"><institution>Lomonosov Moscow State University</institution><country>Russian Federation</country></aff></aff-alternatives><pub-date pub-type="collection"><year>2022</year></pub-date><pub-date pub-type="epub"><day>17</day><month>01</month><year>2023</year></pub-date><volume>23</volume><issue>5</issue><fpage>72</fpage><lpage>86</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Илюхин Д.А., 2023</copyright-statement><copyright-year>2023</copyright-year><copyright-holder xml:lang="ru">Илюхин Д.А.</copyright-holder><copyright-holder xml:lang="en">Ilyukhin D.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/1408">https://www.chebsbornik.ru/jour/article/view/1408</self-uri><abstract><p>В статье изучается проблема Ферма — Торричелли: задача поиска точки, минимизирующей сумму расстояний от неё до некоторых заданных точек в нормированном пространстве. Рассмотрены различные обобщения данной задачи, а также изложены актуальные методы решения и некоторые последние результаты в этой области. Целью работы является поиск ответа на следующий вопрос: в каких нормах на плоскости решение задачи Ферма— Торричелли единственно для любых трёх точек. В работе сформулирован и доказан критерий единственности, кроме того показано применение полученного критерия на нормах, задаваемых правильными многоугольниками, так называемых лямбда-плоскостях.</p></abstract><trans-abstract xml:lang="en"><p>In the paper the Fermat–Torricelli problem is considered. The problem asks a point minimizing the sum of distances to arbitrarily given points in d-dimensional real normed spaces.Various generalizations of this problem are outlined, current methods of solving and some recent results in this area are presented. The aim of the article is to find an answer to the following question: in what norms on the plane is the solution of the Fermat–Torricelli problem unique for any three points. The uniqueness criterion is formulated and proved in the work, in addition, the application of the criterion on the norms set by regular polygons, the so-called lambda planes, is shown.</p></trans-abstract><kwd-group xml:lang="ru"><kwd>проблема Ферма — Торричелли</kwd><kwd>нормирующий функционал</kwd><kwd>лямбда- плоскость.</kwd></kwd-group><kwd-group xml:lang="en"><kwd>Fermat–Torricelli problem</kwd><kwd>norming functional</kwd><kwd>lambda-plane.</kwd></kwd-group><funding-group><funding-statement xml:lang="ru">Работа выполнена при поддержке гранта РНФ 21-11-00355 в МГУ имени М. В. Ломоносова</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">Bajaj C. 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