http://mli7.wordpress.com/2011/03/25/online_learning_expert_problem/
http://www.cvchina.info/2010/05/31/manifold-learning/#more-1038
http://mli7.wordpress.com/2011/03/25/online_learning_expert_problem/
http://www.cvchina.info/2010/05/31/manifold-learning/#more-1038