Description
Add documentation about BPR-MF.
BPR: Bayesian Personalized Ranking from Implicit Feedback. Steffen Rendle, Christoph Freudenthaler, Zeno Gantner and Lars Schmidt-Thieme, Proc. UAI 2009.
https://github.com/myui/hivemall/pull/278
https://gist.github.com/myui/97399188beaf101b87e44dcc73a801d3