99 research outputs found

    {\L}ojasiewicz exponent and pluricomplex Green function on algebraic sets

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    We study pluricomplex Green functions on algebraic sets. Let ff be a proper holomorphic mapping between two algebraic sets. Given a compact set KK in the range of ff, we show how to estimate the pluricomplex Green functions of KK and of f−1(K)f^{-1}(K) in terms of each other, the {\L}ojasiewicz exponent of ff and the growth exponent of ff. This result leads to explicit examples of pluricomplex Green functions on algebraic sets. We also present an enhanced version of the Bernstein-Walsh polynomial inequality specific to algebraic sets. This article provides a theoretical framework for future investigations of the rate of polynomial approximation of holomorphic functions on algebraic sets in the style of Bernstein-Walsh-Siciak theorem

    Evaluating Lebesgue constants by Chebyshev polynomial meshes on cube, simplex and ball

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    We show that product Chebyshev polynomial meshes can be used, in a fully discrete way, to evaluate with rigorous error bounds the Lebesgue constant, i.e. the maximum of the Lebesgue function, for a class of polynomial projectors on cube, simplex and ball, including interpolation, hyperinterpolation and weighted least-squares. Several examples are presented and possible generalizations outlined. A numerical software package implementing the method is freely available online

    Synthesis of Novel, Chiral, Water-Soluble Isothiazole Derivatives.

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