Abstract: An encoder and decoder system for compressing discrete data sequences is disclosed. The encoder includes a self-affine map generator and a backward adaptive map generator which model source vectors formed from a discrete data sequence. The self-affine map generator uses known modeling techniques to determine map parameters for mapping functions. The mapping functions are evaluated by computing a collage error and the mapping function corresponding to the smallest collage error is selected. The backward adaptive map generator determines map parameters for mapping functions which map vectors previously generated to represent the discrete data sequence to the source vector. A distance measurement is computed for each target vector/mapping function combination and the mapping function corresponding to the smallest distance measurement is selected.