\magnification=1200 \baselineskip=20pt \nopagenumbers \font\big=cmr12 scaled \magstep2 \centerline{\bf STANFORD UNIVERSITY} \centerline{\bf DEPARTMENT OF STATISTICS} \centerline{\big DEPARTMENTAL SEMINAR} \bigskip \baselineskip=12pt \centerline{4:15 p.m., Tuesday, April 30, 2002} \centerline{Sequoia Hall Room 200} \centerline{(Cookies at 3:45 in 1st Floor Lounge)} \bigskip \baselineskip=15pt \centerline{\sl Tze Leung Lai} \centerline{\sl Department of Statistics} \centerline{\sl Stanford University} \bigskip \centerline{\bf Filtering, Smoothing and Parameter Estimation in Hidden Markov Models} \bigskip After a brief overview of hidden Markov models and their applications in engineering, economics and bioinformatics, we consider a number of long-standing problems concerning efficient parameter estimation and optimal filters and smoothers when the underlying Markov chain takes values in a general (possibly infinite and multidimensional) state space. We describe certain bounded-complexity approximations and simulation-based methods that are asymptotically as efficient as the computationally intractable maximum likelihood estimators and Bayesian filters and smoothers. \bye