Error: in section 3.4, the statement "The constant s only changes when we update the hyperparameters α" is incorrect, as the number of words in the old topic and the new topic change by one. In fact, s must be updated before and after sampling a topic for each token, but this update takes a constant number of operations, regardless of the number of topics. This problem was only in the paper -- the MALLET implementation has always been correct.