 codice_3; 
codice_4 is the set of hidden states; 
codice_5 is the start probability; 
codice_6 are the transition probabilities; 
and codice_7 are the emission probabilities.For simplicity of code, we assume that the observation sequence codice_2 is non-empty and that codice_9 and codice_10 is defined for all states i,j.In the running example, the forward-backward algorithm is used as follows