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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">mais</journal-id><journal-title-group><journal-title xml:lang="ru">Моделирование и анализ информационных систем</journal-title><trans-title-group xml:lang="en"><trans-title>Modeling and Analysis of Information Systems</trans-title></trans-title-group></journal-title-group><issn pub-type="ppub">1818-1015</issn><issn pub-type="epub">2313-5417</issn><publisher><publisher-name>Yaroslavl State University</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.18255/1818-1015-2018-6-680-691</article-id><article-id custom-type="elpub" pub-id-type="custom">mais-766</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>Оригинальные статьи</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="en"><subject>Articles</subject></subj-group></article-categories><title-group><article-title>О некоторых задачах для симплекса и шара в Rn</article-title><trans-title-group xml:lang="en"><trans-title>On Some Problems for a Simplex and a Ball in Rn</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-6392-7618</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Невский</surname><given-names>Михаил Викторович</given-names></name><name name-style="western" xml:lang="en"><surname>Nevskii</surname><given-names>Mikhail V.</given-names></name></name-alternatives><bio xml:lang="ru"><p>доктор физ.-мат. наук, доцент</p><p>ул. Советская, 14, г. Ярославль, 150003</p></bio><bio xml:lang="en"><p>Doctor of Science</p><p>14 Sovetskaya str., Yaroslavl 150003</p></bio><email xlink:type="simple">mnevsk55@yandex.ru</email><xref ref-type="aff" rid="aff-1"/></contrib></contrib-group><aff-alternatives id="aff-1"><aff xml:lang="ru"><institution>Ярославский государственный университет им. П.Г. Демидова</institution><country>Россия</country></aff><aff xml:lang="en"><institution>P.G. Demidov Yaroslavl State University</institution><country>Russian Federation</country></aff></aff-alternatives><pub-date pub-type="collection"><year>2018</year></pub-date><pub-date pub-type="epub"><day>19</day><month>12</month><year>2018</year></pub-date><volume>25</volume><issue>6</issue><fpage>680</fpage><lpage>691</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Невский М.В., 2018</copyright-statement><copyright-year>2018</copyright-year><copyright-holder xml:lang="ru">Невский М.В.</copyright-holder><copyright-holder xml:lang="en">Nevskii M.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.mais-journal.ru/jour/article/view/766">https://www.mais-journal.ru/jour/article/view/766</self-uri><abstract><p>Пусть \(C\) --- выпуклое тело, \(S\) невырожденный симплекс в \({\mathbb R}^n\). Через \(\tau S\) обозначим образ \(S\) при гомотетии относительно центра тяжести \(S\) с коэффициентом \(\tau\). Под \(\xi(C;S)\) понимается минимальное \(\tau&gt;0,\) для которого \(C\) является подмножеством симплекса \(\tau S\). По определению, \(\alpha(C;S)\) есть минимальное \(\tau&gt;0\), такое что \(C\) принадлежит трансляту симплекса \(\tau S\). Ранее автор доказал, что справедливы равенства \(\xi(C;S)=(n+1)\max\limits_{1\leq j\leq n+1} \max\limits_{x\in C}(-\lambda_j(x))+1\) (если \(C\not\subset S\)), \(\alpha(C;S)= \sum\limits_{j=1}^{n+1} \max\limits_{x\in C} (-\lambda_j(x))+1.\) Здесь \(\lambda_j\) --- линейные функции, называемые базисными многочленами Лагранжа симплекса \(S\). Они таковы, что числа \(\lambda_j(x),\ldots, \lambda_{n+1}(x)\) являются барицентрическими координатами точки \(x\in{\mathbb R}^n\). В предыдущих работах автора указанные формулы исследовались в ситуации, когда \(C\) представляет собой \(n\)-мерный единичный куб \(Q_n=[0,1]^n\). В статье рассматривается случай, когда \(C\) есть единичный евклидов шар \(B_n=\{x: \|x\|\leq 1\},\) где \(\|x\|=\left(\sum\limits_{i=1}^n x_i^2 \right)^{1/2}.\) Устанавливаются различные соотношения для \(\xi(B_n;S)\) и~\(\alpha(B_n;S)\), а также приводится их геометрическая интерпретация. Например, если \(\lambda_j(x)= l_{1j}x_1+\ldots+ l_{nj}x_n+l_{n+1,j},\) то \(\alpha(B_n;S)= \sum\limits_{j=1}^{n+1}\left(\sum\limits_{i=1}^n l_{ij}^2\right)^{1/2}\). Минимальное возможное значение каждой из величин \(\xi(B_n;S)\), \(\alpha(B_n;S)\) для \(S\subset B_n\) равно \(n\) и соответствует правильному симплексу, вписанному в \(B_n\). Даётся сравнение с результатами, полученными ранее для \(C=Q_n\).</p></abstract><trans-abstract xml:lang="en"><p>Let \(C\) be a convex body and let \(S\) be a nondegenerate simplex in \({\mathbb R}^n\). Denote by \(\tau S\) the image of \(S\) under homothety with a center of homothety in the center of gravity of \(S\) and the ratio \(\tau\). We mean by \(\xi(C;S)\) the minimal \(\tau&gt;0\) such that \(C\) is a subset of the simplex \(\tau S\). Define \(\alpha(C;S)\) as the minimal \(\tau&gt;0\) such that \(C\) is contained in a translate of \(\tau S\). Earlier the author has proved the equalities \(\xi(C;S)=(n+1)\max\limits_{1\leq j\leq n+1}\max\limits_{x\in C}(-\lambda_j(x))+1\)  (if \(C\not\subset S\)), \(\alpha(C;S)=\sum\limits_{j=1}^{n+1} \max\limits_{x\in C} (-\lambda_j(x))+1.\)Here \(\lambda_j\) are the linear functions that are called the basic Lagrange polynomials corresponding to \(S\). The numbers \(\lambda_j(x),\ldots, \lambda_{n+1}(x)\) are the barycentric coordinates of a point \(x\in{\mathbb R}^n\). In his previous papers, the author investigated these formulae in the case when \(C\) is the \(n\)-dimensional unit cube \(Q_n=[0,1]^n\). The present paper is related to the case when \(C\) coincides with the unit Euclidean ball \(B_n=\{x: \|x\|\leq 1\},\) where \(\|x\|=\left(\sum\limits_{i=1}^n x_i^2 \right)^{1/2}.\) We establish various relations for \(\xi(B_n;S)\) and \(\alpha(B_n;S)\), as well as we give their geometric interpretation. For example, if \(\lambda_j(x)=l_{1j}x_1+\ldots+l_{nj}x_n+l_{n+1,j},\) then \(\alpha(B_n;S)=\sum\limits_{j=1}^{n+1}\left(\sum\limits_{i=1}^n l_{ij}^2\right)^{1/2}\). The minimal possible value of each characteristics \(\xi(B_n;S)\) and \(\alpha(B_n;S)\) for \(S\subset B_n\) is equal to \(n\). This value corresponds to a regular simplex inscribed into \(B_n\). Also we compare our results with those obtained in the case \(C=Q_n\).</p></trans-abstract><kwd-group xml:lang="ru"><kwd>n-мерный симплекс</kwd><kwd>n-мерный шар</kwd><kwd>гомотетия</kwd><kwd>коэффициент поглощения</kwd></kwd-group><kwd-group xml:lang="en"><kwd>n-dimensional simplex</kwd><kwd>n-dimensional ball</kwd><kwd>homothety</kwd><kwd>absorption index</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">Невский М.В., “Об одном соотношении для минимальной нормы интерполяционного проектора”, Модел. и анализ информ. систем, 16:1 (2009), 24–43;</mixed-citation><mixed-citation xml:lang="en">Nevskij M.V., “On a certain relation for the minimal norm of an interpolational projection”, Modeling and Analysis of Information Systems, 16:1 (2009), 24–43, (in Russian).</mixed-citation></citation-alternatives></ref><ref id="cit2"><label>2</label><citation-alternatives><mixed-citation xml:lang="ru">Невский М.В., “Об одном свойстве n-мерного симплекса”, Матем. заметки, 87:4 (2010), 580–593;</mixed-citation><mixed-citation xml:lang="en">Nevskii M.V., “On a property of n-dimensional simplices”, Math. 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