Singular Integrals with Flag Kernels on Homogeneous Groups: I

Alexander Nagel, Fulvio Ricci, Elias M. Stein +1

Let $\mathcal{K}$ be a flag kernel on a homogeneous nilpotent Lie group $G$. We prove that operators $T$ of the form $T(f)=f\ast \mathcal{K}$ form an algebra under composition, and that…