scholarly journals Pairwise Cosine Similarity of Emission Probability Matrix as an Indicator of Prediction Accuracy of the Viterbi Algorithm

Author(s):  
Guantao Zhao ◽  
Ziqiu Zhu ◽  
Yinan Sun ◽  
Amrinder Arora
2010 ◽  
Vol 08 (03) ◽  
pp. 535-551 ◽  
Author(s):  
IVAN ANTONOV ◽  
MARK BORODOVSKY

We describe a new program for ab initio frameshift detection in protein-coding nucleotide sequences. The task is to distinguish the same strand overlapping ORFs that occur in the sequence due to a presence of a frameshifted gene from the same strand overlapping ORFs that encompass true overlapping or adjacent genes. The GeneTack program uses a hidden Markov model (HMM) of genomic sequence with possibly frameshifted protein-coding regions. The Viterbi algorithm finds the maximum likelihood path that discriminates between true adjacent genes and those adjacent protein-coding regions that just appear to be separate entities due to frameshifts. Therefore, the program can identify spurious predictions made by a conventional gene-finding program misled by a frameshift. We tested GeneTack as well as two earlier developed programs FrameD and FSFind on 17 prokaryotic genomes with frameshifts introduced randomly into known genes. We observed that the average frameshift prediction accuracy of GeneTack, in terms of (Sn + Sp)/2 values, was higher by a significant margin than the accuracy of two other programs. In addition, we observed that the average accuracy of GeneTack is favorably compared with the accuracy of the FSFind-BLAST program that uses protein database search to verify predicted frameshifts, even though GeneTack does not use external evidence. GeneTack is freely available at .


2009 ◽  
Author(s):  
Benjamin Scheibehenne ◽  
Andreas Wilke ◽  
Peter M. Todd
Keyword(s):  

Author(s):  
M. Vidyasagar

This book explores important aspects of Markov and hidden Markov processes and the applications of these ideas to various problems in computational biology. It starts from first principles, so that no previous knowledge of probability is necessary. However, the work is rigorous and mathematical, making it useful to engineers and mathematicians, even those not interested in biological applications. A range of exercises is provided, including drills to familiarize the reader with concepts and more advanced problems that require deep thinking about the theory. Biological applications are taken from post-genomic biology, especially genomics and proteomics. The topics examined include standard material such as the Perron–Frobenius theorem, transient and recurrent states, hitting probabilities and hitting times, maximum likelihood estimation, the Viterbi algorithm, and the Baum–Welch algorithm. The book contains discussions of extremely useful topics not usually seen at the basic level, such as ergodicity of Markov processes, Markov Chain Monte Carlo (MCMC), information theory, and large deviation theory for both i.i.d and Markov processes. It also presents state-of-the-art realization theory for hidden Markov models. Among biological applications, it offers an in-depth look at the BLAST (Basic Local Alignment Search Technique) algorithm, including a comprehensive explanation of the underlying theory. Other applications such as profile hidden Markov models are also explored.


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