Subject: projective representations Date: Tue, 14 Jan 2003 18:55:16 -0500 (EST) From: Ping Xu I wonder if you know any good references on projective representations, and in particular an answer to the following question: Let $G$ be a Lie group, and $\alpaha \in H^3 (BG, Z)$ so that it determines a central extension of $G$. Assume that $\alpha$ is a torsion, i.e., $n \alpha =0$ for some integer $n$. Does $G$ always admit a projective representation? Thanks a lot, Ping Xu