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Search: MSC category 41A17 ( Inequalities in approximation (Bernstein, Jackson, Nikol'skiii-type inequalities) )

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1. CJM 2007 (vol 59 pp. 730)

Erdélyi, T.; Lubinsky, D. S.
Large Sieve Inequalities via Subharmonic Methods and the Mahler Measure of the Fekete Polynomials
We investigate large sieve inequalities such as \[ \frac{1}{m}\sum_{j=1}^{m}\psi ( \log | P( e^{i\tau _{j}}) | ) \leq \frac{C}{2\pi }\int_{0}^{2\pi }\psi \left( \log [ e| P( e^{i\tau }) | ] \right) \,d\tau , \] where $\psi $ is convex and increasing, $P$ is a polynomial or an exponential of a potential, and the constant $C$ depends on the degree of $P$, and the distribution of the points $0\leq \tau _{1}<\tau _{2}<\dots<\tau _{m}\leq 2\pi $. The method allows greater generality and is in some ways simpler than earlier ones. We apply our results to estimate the Mahler measure of Fekete polynomials.


2. CJM 1998 (vol 50 pp. 152)

Min, G.
Inequalities for rational functions with prescribed poles
This paper considers the rational system ${\cal P}_n (a_1,a_2,\ldots,a_n):= \bigl\{ {P(x) \over \prod_{k=1}^n (x-a_k)}, P\in {\cal P}_n\bigr\}$ with nonreal elements in $\{a_k\}_{k=1}^{n}\subset\Bbb{C}\setminus [-1,1]$ paired by complex conjugation. It gives a sharp (to constant) Markov-type inequality for real rational functions in ${\cal P}_n (a_1,a_2,\ldots,a_n)$. The corresponding Markov-type inequality for high derivatives is established, as well as Nikolskii-type inequalities. Some sharp Markov- and Bernstein-type inequalities with curved majorants for rational functions in ${\cal P}_n(a_1,a_2,\ldots,a_n)$ are obtained, which generalize some results for the classical polynomials. A sharp Schur-type inequality is also proved and plays a key role in the proofs of our main results.

Keywords:Markov-type inequality, Bernstein-type inequality, Nikolskii-type inequality, Schur-type inequality, rational functions with prescribed poles, curved majorants, Chebyshev polynomials
Categories:41A17, 26D07, 26C15

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