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Assignments for IIT CS585
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a2: viterbi Algorithm: Hard to Understand #15

Closed changediyasunny closed 7 years ago

changediyasunny commented 7 years ago

Hi Prof, I have couple of doubts implementing viterbi algorithm:

  1. What is the sequence of states S' in viterbi[s,t]←N max s'=1 {viterbi[s',t −1] ∗ a[s',s] ∗ bs(O[t])}

  2. How to calculate viterbi[qf, t] ? viterbi[qF ,T]←N max s'=1 viterbi[s,T] ∗ a[s,qF] How to take final state ? ` This algorithm is getting heavy and very confusing.

aronwc commented 7 years ago

s' is a single state. This definition is specifying how at time t we must consider all possible prior states when computing the max.

For the final state, we just compute the max over the final states in the sequence. Note that in this assignment, you do not need to add artificial "end states."

-Aron

On Sun, Feb 19, 2017 at 11:30 PM, schanged notifications@github.com wrote:

Hi Prof, I have couple of doubts implementing viterbi algorithm:

1.

What is the sequence of states S' in viterbi[s,t]←N max s'=1 {viterbi[s',t −1] ∗ a[s',s] ∗ bs(O[t])} 2.

How to calculate viterbi[qf, t] ? viterbi[qF ,T]←N max s'=1 viterbi[s,T] ∗ a[s,qF] How to take final state ? ` This algorithm is getting heavy and very confusing.

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changediyasunny commented 7 years ago

alright. thank you Prof.