关键词: Carnot群, 正则性, 分数次差商, 非线性次椭圆方程组

Abstract: The paper concerns the regularity of weak solutions for nonlinear subelliptic systems under elliptic and controllable structure conditions on Carnot groups of step two. By the superposition technique of fractional difference quotients, the local HW^2,2estimate of weak solutions is established.

Key words: Carnot group, regularity, fractional difference quotient, nonlinear subelliptic system