A robust approach to sharp multiplier theorems for Grushin operators

Gian Maria Dall'Ara, Alessio Martini

We prove a multiplier theorem of Mihlin-Hörmander type for operators of the form $-{\Delta }_x-V(x){\Delta }_y$ on ${\mathbb{R}}_x^{d_1}\times {\mathbb{R}}_y^{d_2}$, where $V(x) = \sum_{j=1}^{d_1}…