Covariance in Unsupervised Learning of Probabilistic Grammars
Noah A. Smith and Shay B. Cohen

@article{11:101,author={Shay B. Cohen and Noah A. Smith}, Title={Covariance in Unsupervised Learning of Probabilistic Grammars},journal={Journal of Machine Learning Research},volume={11}, url={http://www.jmlr.org/papers/volume11/cohen10a/cohen10a.pdf}}