On the kernel conditions of operators mapping atoms to molecules in local Hardy spaces
In this paper, we explore the relationship between the operators mapping atoms to molecules in local Hardy spaces $h^p(\mathbb{R}^n)$ and the size conditions of its kernel. In particular, we show that if the kernel of a Calder\'on--Zygmund-type operator satisfies an integral-type size condition and a $T^*-$type cancellation, then the operator maps $h^p(\mathbb{R}^n)$ atoms to molecules. On the other hand, assuming that $T$ is an integral type operator bounded on $L^2(\mathbb{R}^n)$ that maps atoms to molecules in $h^p(\mathbb{R}^n)$, then the kernel of such operator satisfies the same integral-type size conditions. We also provide the $L^1(\mathbb{R}^n)$ to $L^{1,\infty}(\mathbb{R}^n)$ boundedness for such operators connecting our integral-type size conditions on the kernel with others presented in the literature.