Hermite–Padé approximation, isomonodromic deformation and hypergeometric integral

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• 作者：Toshiyuki Mano ; Teruhisa Tsuda
• 关键词：Hermite–Padé approximation ; Hypergeometric integral ; Isomonodromic deformation ; Painlevé equation ; Vector continued fraction
• 刊名：Mathematische Zeitschrift
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：285
• 期：1-2
• 页码：397-431
• 全文大小：
• 刊物类别：Mathematics and Statistics
• 刊物主题：Mathematics, general;
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-1823
• 卷排序：285

文摘

We develop an underlying relationship between the theory of rational approximations and that of isomonodromic deformations. We show that a certain duality in Hermite’s two approximation problems for functions leads to the Schlesinger transformations, i.e. transformations of a linear differential equation shifting its characteristic exponents by integers while keeping its monodromy invariant. Since approximants and remainders are described by block-Toeplitz determinants, one can clearly understand the determinantal structure in isomonodromic deformations. We demonstrate our method in a certain family of Hamiltonian systems of isomonodromy type including the sixth Painlevé equation and Garnier systems; particularly, we present their solutions written in terms of iterated hypergeometric integrals. An algorithm for constructing the Schlesinger transformations is also discussed through vector continued fractions.