In incremental IHMM, suppose the i-th span covers two arcs e a and , with probabilities p 1 and p 2 = 1 − p 1 respectively, then the transition from state i to i + 1 jumps across one word (e a ) with probability p 1 and jumps across nothing with probability p 2 .
the transition probability should be Suppose further that the (i + 1)-th span covers two arcs e b and , with probabilities p 3 and p 4 respectively, then the transition from state i to i + 2 covers 4 possible cases: Accordingly the transition probability should be The estimation of transition probability can be generalized to any transition from i to i by expanding all possible n-grams covered by the transition and calculating the corresponding probabilities.