1. A method comprising: representing, by use of a processor, state transition probabilities between a plurality of statistical Markov model-like states (plurality of states) and output probabilities associated with a plurality of previous statistical Markov model-like states (plurality of previous states), wherein the state transition probabilities between the plurality of previous states depend on a sequence of previous states of the plurality of previous states and the output probabilities associated with each of the plurality of states depend on the sequence of previous states; and calculating a state transition probability for the plurality of states.