Viterbi getting a little better

I have implemented an "isPrefix" function in Matlab that works fine. The problem is that I don't know how to incorporate it into the Viterbi algorithm. Instead of using that, I have a function that takes in a character and an index and returns true if there exists a string in the roster with that character at that index, and false otherwise. I use this function when assigning emission probabilities - I only assign a character a positive emission probability if this character could be for realz.

Now the algorithm guesses "william clinton" correctly, but "lyndon johnson" it now guesses to be "lildon joreron", and "gerald ford" to be "georicarin". This algorithm will work especially badly for large rosters where the function taking in a character and an index will almost always return true. However with my small roster of 7 this function has helped.

Instead of having an "isPrefix" function, I plan to implement an "isSuffix" function because of the way that the Viterbi algorithm works when finding the most likely sequence. It starts at the end and works its way backwards.