Recognition of incomplete sequences described by hidden Markov models using first derivatives of likelihood function logarithm
Hidden Markov model (HMM) conception was presented yet in 1970-s, however problems which concern using HMMs in case of incomplete data remain poorly investigated. These problems are quite relevant since in complex systems, e.g. when receiving signals from spacecrafts or aircrafts, one has to deal with datastreams of various sources in noisy environments when there is a high possibility of data loss or corruption. In this paper, we deal with the problem of missing observations in sequences. From now on we will refer to such sequences as incomplete. We consider a case when such missing observations are not generated by random process itself but rather occur randomly in sequences because of some external interference. We propose a method for recognition of incomplete sequences which is based on classification of incomplete sequences using first derivatives of likelihood function logarithm with respect to various HMM parameters. We use a support vector machine classifier for that purpose. The likelihood in that case is the probability of incomplete sequence being generated by a HMM. The proposed method was compared to a previously developed method for recognition based on marginalization of missing observations. The proposed method proved to be more effective than the other method in situation when the number of missing observations in training and testing sequences is high (more than 20% in our particular experiment). Thus, we propose to prefer the usage of the proposed method in situations when there is big loss of data but the recognition is still had to be done.
Keywords
скрытые марковские модели, машинное обучение, последовательности, пропущенные наблюдения, неполные данные, hidden Markov models, machine learning, sequences, missing observations, incomplete dataAuthors
Name | Organization | |
Uvarov Vadim E. | Novosibirsk State Technical University | uvarov.vadim42@gmail.com |
References

Recognition of incomplete sequences described by hidden Markov models using first derivatives of likelihood function logarithm | Vestnik Tomskogo gosudarstvennogo universiteta. Upravlenie, vychislitelnaja tehnika i informatika – Tomsk State University Journal of Control and Computer Science. 2018. № 42. DOI: 10.17223/19988605/42/9