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C. Cascante

Publications and source records attributed to C. Cascante.

3 recordsLinked to original sources

On the radicality property for spaces of symbols of bounded Volterra operators

In a recent paper of the authors together with A. Aleman, it is shown that the Bloch space $\mathcal{B}$ in the unit disc has the following radicality property: if an analytic function $g$ satisfies that $g^n\in \mathcal{B}$, then $g^m\in \mathcal{B}$, for all $m\le n$. Since $\mathcal{B}$ coincides with the space $\mathcal{T}(A^p_α)$ of analytic symbols $g$ such that the Volterra-type operator $T_gf(z)= \int_0^z f(ζ)g'(ζ)\,dζ$ is bounded on the classical weighted Bergman space $A^p_α$, the radicality property was used to study the composition of paraproducts $T_g$ and $S_gf=T_fg$ on $A^p_α$. Motivated by this fact, we prove that $\mathcal{T}(A^p_ω)$ also has the radicality property, for any radial weight $ω$. Unlike the classical case, the lack of a precise description of $\mathcal{T}(A^p_ω)$ for a general radial weight, induces us to prove the radicality property for $A^p_ω$ from precise norm-operator results for compositions of analytic paraproducts.

math.CV

Nonlinear potentials and two weight trace inequalities for general dyadic and radial kernels

We study trace inequalities of the type $$ \| T_k f\|_{L^q(dμ)}\leq C \|f\|_{L^p(dσ)}, \qquad f \in L^p(dσ), $$ in the ``upper triangle case'' $1 \leq q<p$ for integral operators $T_k$ with positive kernels, where $dσ$ and $dμ$ are positive Borel measures on $\R^n$. Our main tool is a generalization of Th. Wolff's inequality which gives two-sided estimates of the energy ${\mathcal E}_{k, σ} [μ]=\int_{\R^n} (T_k [μ])^{p'} d σ$ through the $L^1(dμ)$-norm of an appropriate nonlinear potential $W_{k, σ}[μ]$ associated with the kernel $k$ and measures $dμ$, $d σ$. We initially work with a dyadic integral operator with kernel $K_{\mathcal D}(x, y) = \sum_{Q\in{\mathcal D}} K(Q) χ_Q(x) χ_Q(y)$, where $\mathcal D=\{Q\}$ is the family of all dyadic cubes in $\R^n$, and $K: {\mathcal D}\to \R^+$. The corresponding continuous versions of Wolff's inequality and trace inequalities are derived from their dyadic counterparts.

math.FA