Parameter Estimation I
Given a certain observation sequence, we want to find the values of the model parameters ?=(A, B, ?) which best explain what we observed.
Using Maximum Likelihood Estimation, we can want find the values that maximize P(O| ?), i.e. argmax ? P(Otraining| ?)
There is no known analytic method to choose ? to maximize P(O| ?). However, we can locally maximize it by an iterative hill-climbing algorithm known as Baum-Welch or Forward-Backward algorithm. (special case of the EM Algorithm)