DNA sequence compression using the normalized maximum likelihood model for discrete regression

The use of normalized maximum likelihood (NML) model for encoding sequences known to have regularities in the form of approximate repetitions was discussed. A particular version of the NML model was presented for discrete regression, which was shown to provide a very powerful yet simple model for encoding the approximate repeats in DNA sequences. Combining the model of repeats with a simple first order Markov model, a fast lossless compression method was obtained that compares favorably with the existing DNA compression programs. It is remarkable that a simple model, which recursively updates a small number of parameters, is able to reach the state of the art compression ratio for DNA sequences with much more complex models. Being a minimum description length (MDL) model, the NML model may later prove to be useful in studying global and local features of DNA or possibly of other biological sequences.