@Article{ATA-30-4, author = {}, title = {$L^q$ Inequalities and Operator Preserving Inequalities}, journal = {Analysis in Theory and Applications}, year = {2014}, volume = {30}, number = {4}, pages = {377--386}, abstract = {

Let $\mathbb{P}_n$ be the class of polynomials of degree at most $n$. Rather and Shah [15] proved that if $P\in \mathbb{P}_n$ and  $P(z)\neq 0$ in $|z| < 1$, then for every $R  > 0$ and 0 $\leq q < \infty, $ $$| B[P(Rz)]|_q \leq  \frac{| R^{n}B[z^n] +\lambda_0 |_{q}}{| 1+z^n|_q} | P(z)|_q,$$where $B$ is a $ B_{n}$-operator.
In this paper, we prove some generalization of this result which in particular yields some known polynomial inequalities as special. We also consider an operator $D_{\alpha}$ which maps a polynomial $P(z)$ into $D_{\alpha} P(z) := n P(z) + ( \alpha - z ) P' (z)$ and obtain extensions and generalizations of a number of well-known $L_{q}$ inequalities.

}, issn = {1573-8175}, doi = {https://doi.org/10.4208/ata.2014.v30.n4.5}, url = {https://global-sci.com/article/74006/lq-inequalities-and-operator-preserving-inequalities} }