Quizz 3 Question 2-3

Quizz 3 Question 2-3

par Taha Zakariya,
Nombre de réponses : 3

Hello,

I'd like to ask about the questions that concern the application of Viterbi from the last quizz.

Having constructed the viterbi graph, I get for example for w2 the two following values: 0.0144 for N and 0.0032 for V (at the end the most probable sequence goes through N). We saw in the course that Viterbi keeps the max value, so I don't get why for "the node associated with V for the word "w2" " the answer is 0.0032. Same thing for the next one, we keep the lower value which is also the one that isn't included in the most probable sequence. Could you please give me some clarification on this matter?

Thanks.

En réponse à Taha Zakariya

Re: Quizz 3 Question 2-3

par Deniz Bayazit,
I think this was answered today in-person. Let me know if something is still not clear!
En réponse à Deniz Bayazit

Re: Quizz 3 Question 2-3

par Issam Arabi,
Can you explain how we got the answer for q2 and q3?
En réponse à Issam Arabi

Re: Quizz 3 Question 2-3

par Jean-Cédric Chappelier,
you have to "accumulate" (multiply) the probabilities along the path (Pinit * Pemit_1 + Ptransition_1_to_2 * Pemit_2 * Ptransition_2_to_3 * Pemit_3 *....), taking the max at each step.
In your case:
Q2 : 0.8 * 0.2 * 0.1 * 0.2 = .0032 (no max to take here since no ambiguity)
Q3 : 0.8 * 0.2 * max(0.9 * 0.1 * 0.5 , 0.1 * 0.2 * 0.4) * 0.3 = 0.8 * 0.2 * 0.9 * 0.1 * 0.5 * 0.3 = 0.00216