Weak (1,1) Shur multipliers and the Hörmander--Mikhlin--Schur theorem

Yongqiang Tian

Let $S_m$ be the Schur multiplier with symbol $m$. We characterize the boundedness of $S_m:{\mathcal{S}}^1\to {\mathcal{S}}^{1,\infty }$ by approximation of weighted columns in a common fi…