On Helson matrices: moment problems, non-negativity, boundedness, and finite rank

Karl-Mikael Perfekt, Alexander Pushnitski

We study Helson matrices (also known as multiplicative Hankel matrices), i.e. infinite matrices of the form $M(\alpha )=\{\alpha (nm){\}}_{n,m=1}^{\infty }$, where $\alpha$ is a sequence of complex nu…