Some remarks on Toeplitz multipliers and Hankel matrices}
Tom 175 / 2006
Streszczenie
Consider the set of all Toeplitz–Schur multipliers sending every upper triangular matrix from the trace class into a matrix with absolutely summable entries. We show that this set admits a description completely analogous to that of the set of all Fourier multipliers from $H_1$ into $\ell_1$. We characterize the set of all Schur multipliers sending matrices representing bounded operators on $\ell_2$ into matrices with absolutely summable entries. Next, we present a result (due to G. Pisier) that the upper triangular parts of such Schur multipliers are precisely the Schur multipliers sending upper triangular parts of matrices representing bounded linear operators on $\ell_2$ into matrices with absolutely summable entries. Finally, we complement solutions of Mazur's Problems 8 and 88 in the Scottish Book concerning Hankel matrices.
