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Questions tagged [viterbi-algorithm]

An algorithm for finding the most probable sequence of latent variables in a directed graphical model, using dynamic programming.

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Inferring Hidden States in Hidden Markov Models

To decode an HMM, the usual approach is use the Viterbi algorithm where the probability of the most likely sequence of hidden states $z_1,..,z_n$ generating the observations $y_1,..,y_n$ is given by: \...
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Amortized complexity of viterbi algorithm for first-order HMM

The Viterbi algorithm is a dynamic programming algorithm for obtaining the maximum a posteriori probability estimate of the most likely sequence of hidden states—called the Viterbi path—that results ...
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What is the difference between the Viterbi algorithm and beam search?

I'm just confused because I'm having trouble wrapping my head around the difference. If we were to set the beam size to be equal to the number of possible states, wouldn't that mean the beam search ...
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modification of variable elimination for underflow

In Daphne Kollers book on Probabilistic graphical models exercise 9.3 asks the following Ex 9.3 Consider a modified variable elimination algorithm that is allowed to multiply all of the entries in a ...
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Using Forward Backward algorithm to find posterior probability of all possible states

I understand that Viterbi finds the most probable sequence of states. However, I want the probability of all possible sequences of states. I understand that FB algorithm can be used to find the ...
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Can I transform the Viterbi score from tensorflow into a probability?

I understand the Viterbi algorithm as it is explained in Wikipedia However, the TensorFlow implementation is different: ...
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Viterbi Algorithm - Most likely sequence vs sequence of most likely states

I'm trying to understand why the following pseudo-code function is correct: ...
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Efficiency of Viterbi Algorithm

Considering that we have a sequence of observed states $\{y_1, y_2, \dots, y_T \}$ of length $T$. We want to generate a path $\{x_1, x_2, \dots, x_T\}$, which is a sequence of states $x_n \in S = \{...
Gustavo Rangel's user avatar
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Optimizing production program

As part of the production of masscustomization products, I have to solve the following problem. A fixed set of sequences (changes from one product to another) is associated with a percentage value of ...
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Viterbi Algorithm [closed]

Can someone explain why Is it because for the left argument, we would find the most likely sequence of states given observations and for the right argument, we would eventually find the most likely ...
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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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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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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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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 ...
stack's user avatar
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1 answer
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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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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 ...
Roman's user avatar
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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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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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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 ...
Kevvy Kim's user avatar
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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 ...
Hande's user avatar
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11 votes
2 answers
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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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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. ...
user308485's user avatar
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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 ...
Abbas's user avatar
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10 votes
1 answer
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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, ...
minerals's user avatar
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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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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 .....
Rudy Wijanarko's user avatar
2 votes
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205 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?
user22062's user avatar
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56 votes
5 answers
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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.
user34790's user avatar
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22 votes
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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.
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