Speaker : Professor Chin-Tung Wu(National Pingtung University of Education) CR Obata Theorem for Kohn Laplacian 2012-11-15 (Thu) 15:00 - 16:00 Lecture Hall, Inst. of Mathematics In this talk, we first show the CR Lichnerowicz theorem for Kohn Laplacian in a closed pseudohermitian (2n+1)-manifold (M,θ). Secondly, we confirm the corresponding CR Obata theorem in a closed (2n+1)-manifold M with a volume-normalized contact form θ. In particular, it is true for a closed pseudohermitian hypersurface in $C^{n+1}$. This is a join work with Prof. Shu-Cheng Chang.