# 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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### Baum-Welch Algorithm and Viterbi Algorithm

Given a sequence of actual states which is assumed to be the sequence that has the maximum likelihood of causing an observed sequence of states, is it possible to find the parameters such that when ...
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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 ...
78 views

### 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 ...
1 vote
123 views

### 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 ...
1 vote
188 views

### 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: ...
375 views

### Viterbi Algorithm - Most likely sequence vs sequence of most likely states

I'm trying to understand why the following pseudo-code function is correct: ...
1 vote
198 views

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 = \{... 0 votes 1 answer 24 views ### 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 ... 0 votes 1 answer 44 views ### 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 ... 1 vote 0 answers 82 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/... 1 vote 1 answer 625 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 ... 5 votes 1 answer 884 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 (... 1 vote 0 answers 244 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 ... 1 vote 1 answer 115 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? 1 vote 0 answers 196 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 ... 1 vote 1 answer 99 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, ... 1 vote 1 answer 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 ... 0 votes 1 answer 723 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 ... 2 votes 0 answers 1k 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 ... 10 votes 2 answers 10k 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}}$) and ... 2 votes 0 answers 38 views ### How large a training set do I need for an English POS tagger? I'm trying to implement a POS tagger for English using the Viterbi algorithm on an HMM model. Right now, my results are poor and I'm not sure whether it's due to a bug or due to lack of training data. ... 0 votes 1 answer 659 views ### In what way does clustering help in classification? I understand that with a K-means or DTW algorithm one can cluster time series using a distance criterion, i also understand that with a K-NN algorithm for example one can do pattern recognition and ... 8 votes 1 answer 10k views ### Explain Backward algorithm for Hidden Markov Model I have implemented Viterbi and Forward algorithm, alas strangely I can't understand how does Backward algorithm work. Intuitively I feel like I need to do the same thing as in Forward only backwards, ... 0 votes 0 answers 250 views ### Using Viterbi Algorithm to find the most probable sequence I have this problem, but I couldn't find any related literature. Let's assume that I have this arrival process (the system can fit just one user): With probability$P_a\$ the next user is from class ... 160 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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### 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?