论文标题

奇数多项式近似奇数函数的近似失败

Failure of Approximation of Odd Functions by Odd Polynomials

论文作者

Mashreghi, Javad, Parisé, Pierre-Olivier, Ransford, Thomas

论文摘要

我们在设备磁盘上构建了Hilbert Holomorthic函数$ H $ $ H $,以使多项式在$ H $中密集,但是奇数多项式在$ H $中的奇数函数中并不密集。结果,存在一个函数$ f $ in $ h $中的$ f $,该函数位于其taylor partial sugs $ s_n(f)$之外,因此无法通过应用于$ s_n(f)$的任何三角形总和方法来近似。我们还表明,存在$ h $中的功能$ f $,其径向封闭的线性跨度扩大了$ f_r,〜r <1 $。

We construct a Hilbert holomorphic function space $H$ on the unit disk such that the polynomials are dense in $H$, but the odd polynomials are not dense in the odd functions in $H$. As a consequence, there exists a function $f$ in $H$ that lies outside the closed linear span of its Taylor partial sums $s_n(f)$, so it cannot be approximated by any triangular summability method applied to the $s_n(f)$. We also show that there exists a function $f$ in $H$ that lies outside the closed linear span of its radial dilates $f_r, ~r<1$.

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