@article {49836, title = {Estimating Tree-Structured Covariance Matrices via Mixed-Integer Programming}, journal = {J Mach Learn Res}, volume = {5}, year = {2009}, pages = {41-48}, chapter = {41}, author = {Corrada Bravo, Hector and Wright, Stephen and Eng, Kevin H. and Keles, S{\"u}nd{\"u}z and Wahba, Grace} }