Ralf Herbrich Tom Minka Thore Graepel TrueSkill<sup>TM</sup>: A Bayesian Skill Rating System. 569-576 2006 conf/nips/2006 NIPS http://books.nips.cc/papers/files/nips19/NIPS2006_0688.pdf db/conf/nips/nips2006.html#HerbrichMG06