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# Wydawnictwa / Czasopisma IMPAN / Studia Mathematica / Wszystkie zeszyty

## A Hankel matrix acting on Hardy and Bergman spaces

### Tom 200 / 2010

Studia Mathematica 200 (2010), 201-220 MSC: Primary 47B35; Secondary 30H10. DOI: 10.4064/sm200-3-1

#### Streszczenie

Let $\mu$ be a finite positive Borel measure on $[0,1).$ Let ${\cal H}_\mu=(\mu_{n,k})_{n,k\geq 0}$ be the Hankel matrix with entries $\mu_{n,k}=\int_{[0,1)} t^{n+k}\,d\mu(t).$ The matrix $\mathcal{H}_{\mu}$ induces formally an operator on the space of all analytic functions in the unit disc by the fomula $${\cal H}_\mu(f)(z)=\sum_{n=0}^\infty\Bigl(\sum_{k= 0}^\infty\mu_{n,k}a_k\Bigr)z^n,\ \quad z\in {\mathbb D},$$ where $f(z)=\sum_{n=0}^\infty a_n z^n$ is an analytic function in $\mathbb D$.

We characterize those positive Borel measures on $[0,1)$ such that ${\cal H}_\mu(f)(z)= \int_{[0,1)}\frac{f(t)}{1-tz}\,d\mu(t)$ for all $f$ in the Hardy space $H^1$, and among them we describe those for which ${\cal H}_\mu$ is bounded and compact on $H^1$. We also study the analogous problem for the Bergman space $A^2$.

#### Autorzy

• Petros GalanopoulosDepartamento de Análisis Matemático
Campus de Teatinos, 29071 Málaga, Spain
e-mail
• José Ángel PeláezDepartamento de Análisis Matemático