TY - JOUR T1 - Liouville Type Theorems of Semilinear Equations with Square Sum of Vector Fields JO - Journal of Partial Differential Equations VL - 2 SP - 149 EP - 153 PY - 2005 DA - 2005/05 SN - 18 DO - http://doi.org/ UR - https://global-sci.org/intro/article_detail/jpde/5351.html KW - Liouville type theorem KW - superlinear equation KW - local Hörmander condition KW - square sum operator KW - generalized cone domain AB - Let X_j ; j = 1, …, k, be first order smooth quasi-homogeneous vector fields on Rn with the property that the dimension of the Lie algebra generated by these vector fields is n at x = 0 and X^∗_j = -X_j, j = 1, …, k. Let L = \sum^k_{i=1} X²_i . In this paper, we study the nonnegative solutions of semilinear equation Lu + f(x, u) = 0 (or ≤ 0 ) in Rn and generalized cone domain, respectively, and prove that the solutions must be vanish under some suitable conditions.