Questions tagged [viterbi-algorithm]

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Markov Decision Process augmented with latent/hidden variables but does not use a belief state distribution (what do we call this?)

I have a Markov Decision Process where packets arrive to a queue which services them. It has a high cost fast setting and a low cost slow setting. Usually the arrival rates are assumed to follow some ...
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0answers
38 views

What is HMM and Viterbi algorithm?

I have to learn what is HMM and Viterbi alogrithm, I search all pages on Google, but I can't understand what is HMM is and what is Viterbi is, if there is very basic and very simple examples/...
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1answer
186 views

Viterbi algorithm for finding most probable path with varying transition probabilities

I'm struggling to apply the Viterbi algorithm to a simple case of inferring hidden states where the transmission probabilities change. I've draw a picture below of the trellis with transition ...
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1answer
422 views

Viterbi and forward-backward algorithm in HMM

I am learning HMM recently and got confused with the training problem (training model parameters and hidden state given outcome sequence). As far as I know, both Viterbi learning and Baum-Welch (...
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157 views

Classification Using The Hidden Markov Model

I am having difficulty understanding certain concepts regarding the classification using HMM. There are numerous post here and in the internet about that, but they never get to detail or they all ...
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1answer
61 views

Can all or most combinatoric optimization problems in Machine Learning be solved using Viterbi algorithm? [closed]

I am just scratching the surface of the topic but are there practical limitations even for Viterbi Algorithm? Also, are Viterbi Algorithm and dynamic programming equivalent?
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141 views

What if transitions and emissions in a hidden Markov model are not independent?

A Hidden Markov Model is given by transition and emission matrices. The transition matrix determine probability of "next states" as a function of the current state. The emission matrix determine the ...
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1answer
56 views

Produce Multiple Sequence Alignments using Profile HMMs

I have a few multiple sequence alignments and a few groups (let's say N) of unaligned sequences. I would like to learn the emission and transition probabilities from the multiple sequence alignments, ...
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1answer
566 views

Decode the most likely sequence of states for the following sequence

A two-state HMM is constructed from the measurements shown below. The mean length indicates the average time that the HMM stays in the state. Decode the most likely sequence of states (P/Y) for ...
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1answer
2k views

Matlab hmm viterbi algorithm calculated state sequence Probability

I have used matlab hmmviterbi function in my code for calculating the most probable state sequence from observation sequence. Is there any way to derive the probability (score) of this calculated ...
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1answer
645 views

Other method to find the most likely hidden state in HMM?

If I use Baum-Welch algorithm to best estimate the parameters for hidden Markov model, then I was thinking, instead of using Viterbi algorithm, why can't I just find the most likely hidden state for ...
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924 views

HMM for sequence classification in R

I have a dataset which includes sequence of DNA nucleotides (A,C,G,T) and each sequence has a gene index that is binary. i.e I'm trying to classify unknown sequence by using a hidden markov model in ...
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2answers
8k views

Calculating Emission Probability values for Hidden Markov Model (HMM)

I'm new to HMM and still learning. I'm currently using HMM to tag part-of-speech. To implement the viterbi algorithm I need transition probabilities ($ a_{i,j} \newcommand{\Count}{\text{Count}}$) and ...
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0answers
31 views

How large a training set do I need for an English POS tagger?

I'm trying to implement a POS tagger for English using the Viterbi algorithm on an HMM model. Right now, my results are poor and I'm not sure whether it's due to a bug or due to lack of training data. ...
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1answer
483 views

In what way does clustering help in classification?

I understand that with a K-means or DTW algorithm one can cluster time series using a distance criterion, i also understand that with a K-NN algorithm for example one can do pattern recognition and ...
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1answer
7k views

Explain Backward algorithm for Hidden Markov Model

I have implemented Viterbi and Forward algorithm, alas strangely I can't understand how does Backward algorithm work. Intuitively I feel like I need to do the same thing as in Forward only backwards, ...
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0answers
229 views

Using Viterbi Algorithm to find the most probable sequence

I have this problem, but I couldn't find any related literature. Let's assume that I have this arrival process (the system can fit just one user): With probability $P_a$ the next user is from class ...
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0answers
156 views

Predicting Trend using Hidden Markov Model

I am trying to predict exchange rates trend using Hidden Markov model (Viterbi Algorithm). For 2 state trending, I use A = [0.9 0.1; 0.1 0.9] as transition matrix and B = [1/N 1/N ....1/N; 1/N 1/N .....
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184 views

What is the difference between coupled HMM's viterbi algorithm and tranditional HMM's viterbi algorithm?

Can anyone show me what is the difference between coupled HMM's viterbi algorithm and tranditional HMM's viterbi algorithm? Is there any examples?
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5answers
44k views

What is the difference between the forward-backward and Viterbi algorithms?

I want to know what the differences between the forward-backward algorithm and the Viterbi algorithm for inference in hidden Markov models (HMM) are.
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2answers
22k views

What are the differences between the Baum-Welch algorithm and Viterbi training?

I am currently using Viterbi training for an image segmentation problem. I wanted to know what the advantages/disadvantages are of using the Baum-Welch algorithm instead of Viterbi training.