http://www.jmlr.org/papers/volume13/larochelle12a/larochelle12a.pdf http://machinelearning.org/archive/icml2008/papers/601.pdf
http://www.jmlr.org/papers/volume13/larochelle12a/larochelle12a.pdf
http://machinelearning.org/archive/icml2008/papers/601.pdf