Computable bounds of an πΒ²-spectral gap for discrete Markov chains with band transition matrices
AbstractWe analyse the πΒ²(π)-convergence rate of irreducible and aperiodic Markov chains with N-band transition probability matrix P and with invariant distribution π. This analysis is heavily based on two steps. First, the study of the essential spectral radius ress(P|πΒ²(π)) of P|πΒ²(π) derived from Hennionβs quasi-compactness criteria. Second, the connection between the spectral gap property (SG2) of P on πΒ²(π) and the V-geometric ergodicity of P. Specifically, the (SG2) is shown to hold under the condition Ξ±0ββm=βNNlimβsupiβ+β(P(i,i+m)P*(i+m,i)1β2<1. Moreover, ress(P|πΒ²(π)β€Ξ±0. Effective bounds on the convergence rate can be provided from a truncation procedure.