${L^p}$-Liouville Theorems for Invariant Partial Differential Operators   in ${\mathbb{R}^n}$
  We prove some $L^p$-Liouville theorems for hypoelliptic second order Partial Differential Operators left translation invariant with respect to a Lie group composition law in $\mathbb{R}^n$. Results for both solutions and subsolutions are given. 
Alessia E. Kogoj and Ermanno Lanconelli
math.AP