Pseudo-differential operators on $\mathbb{Z}^n$ with applications to discrete fractional integral operators

In this manuscript we provide necessary and sufficient conditions for the $\textnormal{weak}(1,p)$ boundedness, $1< p<\infty,$ of discrete Fourier multipliers (Fourier multipliers on $\mathbb{Z}^n$). Our main goal is to apply the results obtained to discrete fractional integral operators. Discrete versions of the Calder\'on-Vaillancourt Theorem and the Gohberg Lemma also are proved.