Volume no :4, Issue no: 1, September (2010)

POLYNOMIAL APPROXIMATIONS FOR ESTIMATION OF HIDDEN MARKOV MODEL'S PARAMETERS

Author's: J. A. Boguslavskiy
Pages: [1] - [23]
Received Date: August 31, 2010
Submitted by:

Abstract

Motivation. The Baum-Welch-algorithm usually recommend for an estimation of parameters HMM. However, it not reliable as supplies the vector of estimations, which as soon as corresponds to some nearness to one of local maxima likelihood.

Results. This paper offers for estimation new MPA-algorithm, which by means of polynomial approximations, the Bayes approach, and a compression of an information builds approximations to a vector of the conditional expectation. It is considered example, where HMM for r=4 observable symbols and for s=5 hidden states generates multiple sequences 15000 observable characters. The MPA-algorithm calculates the estimates of the unknown 25 transition probabilities and 20 emission probabilities by means of polynomial approximations 3 orders. It has appeared, that from 45 relative errors of an estimation almost all are less 0.1. Input MPA-algorithm were 16 numbers of the experimental frequencies received by compression of the primary information.

Keywords

hidden Markov model, stochastic matrix, probabilistic function, polynomial approximation, estimation, conditional expectations.