Variables over intermediate f t and modeled q t states are factored into sequences of depth-specific variablesone for each of D levels in the HMM hierarchy: Transition probabilities are then calculated as a product of transition probabilities at each level, using level-specific 'reduce' Θ F and 'shift' Θ Q models: with f D+1 t and q 0 t defined as constants.
in Figure 2, the same repair is shown as it appears in the training data for this system.