1. A method of generating probabilities to calculate log-likelihood values corresponding to data in a maximum a posteriori processor, the method comprising the steps of: (a) generating a set of &agr; values as forward probabilities of a trellis for a current state; and (b) deleting selected values of the set of &agr; values based on an a posteriori probability (APP) value having at least two previous states to provide a reduced set of &agr; values corresponding to the data.