A survey of smoothing techniques for ME models

In certain contexts, maximum entropy (ME) modeling can be viewed as maximum likelihood (ML) training for exponential models, and like other ML methods is prone to overfitting of training data. Several smoothing methods for ME models have been proposed to address this problem, but previous results do not make it clear how these smoothing methods compare with smoothing methods for other types of related models. In this work, we survey previous work in ME smoothing and compare the performance of several of these algorithms with conventional techniques for smoothing n-gram language models. Because of the mature body of research in n-gram model smoothing and the close connection between ME and conventional n-gram models, this domain is well-suited to gauge the performance of ME smoothing methods. Over a large number of data sets, we find that fizzy ME smoothing performs as well as or better than all other algorithms under consideration. We contrast this method with previous n-gram smoothing methods to explain its superior performance.