Christopher Tosh, Sanjoy Dasgupta. Maximum Likelihood Estimation for Mixtures of Spherical Gaussians is NP-hard. Journal of Machine Learning Research, 18, 2017. [doi]
@article{ToshD17-0,
title = {Maximum Likelihood Estimation for Mixtures of Spherical Gaussians is NP-hard},
author = {Christopher Tosh and Sanjoy Dasgupta},
year = {2017},
url = {http://jmlr.org/papers/v18/papers/v18/16-657.html},
researchr = {https://researchr.org/publication/ToshD17-0},
cites = {0},
citedby = {0},
journal = {Journal of Machine Learning Research},
volume = {18},
}