On the sharpness of one inequality of different metrics for algebraic polynomials
We prove that the previously established inequality of different metrics for algebraic polynomials is sharp in the sense of order.
arXiv subjects
Publications and source records attributed to Roman Veprintsev.
We prove that the previously established inequality of different metrics for algebraic polynomials is sharp in the sense of order.
We establish an inequality of different metrics for algebraic polynomials.
We obtain Paley-type and Hausdorff-Young-Paley-type inequalities for Jacobi expansions.
Using Dunkl theory, we introduce into consideration some weighted $L_p$-spaces on $[-1,1]$ and on the unit Euclidean sphere $\mathbb{S}^{d-1}$, $d\geq 2$. Then we define a family of linear bounded operators $\{V_κ^p(x)\colon x\in\mathbb{S}^{d-1}\}$ acting from the $L_p$-space on $[-1,1]$ to the $L_p$-space on $\mathbb{S}^{d-1}$, $1\leq p<\infty$. We establish a necessary and sufficient condition for a function $g$ belonging to the $L_p$-space on $[-1,1]$ such that the family of functions $\{V_κ^p(x;g)\colon x\in\mathbb{S}^{d-1}\}$ is fundamental in the $L_p$-space on $\mathbb{S}^{d-1}$.
We establish Paley-type and Hausdorff-Young-Paley-type inequalities for generalized Gegenbauer expansions.
We establish a necessary and sufficient condition on a continuous function on $[-1,1]$ under which the family of functions on the unit sphere $\mathbb{S}^{d-1}$ constructed in the described manner is fundamental in $C(\mathbb{S}^{d-1})$. In our construction of functions and proof of the result, we essentially use Dunkl harmonic analysis.
Using well-known techniques, we establish Hardy-Littlewood-type and Hausdorff-Young-type inequalities for generalized Gegenbauer expansions and their unification.
Using well-known facts on Jacobi polynomials, we derive some asymptotic estimates for the maximum absolute value of generalized Gegenbauer polynomials.