... enabled in-stead the use of infinite models, in which thenumber of hidden categories is not fixed, butcan grow with the amount of training data.Here we develop the infinite tree, a new infi-nite ... complex model forms, so as toallow multiple, group-specific, infinite mixture mod-els to share their mixture components. The closelyrelated infinite hidden Markov model is an HMMin which the transitions ... et al., 2006).We extend this work by introducing the infinite tree model, which represents recursive branchingstructure over a potentially infinite set of hiddenstates. Such models are appropriate...