On the role of pattern matching in information theory

In this paper, the role of pattern matching in information theory is motivated and discussed. We describe the relationship between a pattern's recurrence time and its probability under the data-generating stochastic source. We show how this relationship has led to great advances in universal data compression. We then describe nonasymptotic uniform bounds on the performance of data-compression algorithms in cases where the size of the training data that is available to the encoder is not large enough so as to yield the asymptotic compression: the Shannon entropy. We then discuss applications of pattern matching and universal compression to universal prediction, classification, and entropy estimation.