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A Bayesian Nonparametric Model for Spectral Estimation of Metastable Systems
Proceedings of the 30th Conference on Uncertainty in Artificial Intelligence, PMLR R12:922-931, 2014.
Abstract
The identification of eigenvalues and eigenfunctions from simulation or experimental data is a fundamental and important problem for analysis of metastable systems, because the dominant spectral components usually contain a lot of essential information of the metastable dynamics on slow timescales. It has been shown that the dynamics of a strongly metastable system can be equivalently described as a hidden Markov model (HMM) under some technical assumptions and the spectral estimation can be performed through HMM learning. However, the spectral estimation with unknown number of dominant spectra is still a challenge in the framework of traditional HMMs, and the infinite HMMs developed based on stick-breaking processes cannot satisfactorily solved this problem either. In this paper, we analyze the difficulties of spectral estimation for infinite HMMs, and present a new nonparametric model called stick-breaking half-weighted model (SB-HWM) to address this problem. The SB-HWM defines a sparse prior of eigenvalues and can be applied to Bayesian inference of dominant eigenpairs of metastable systems in a nonparametric manner. We demonstrate by simulations the advantages of applying SB-HWM to spectral estimation.