Stopping times and directed processes

by Gerald A. Edgar

"In this book the technique of stopping times is applied to prove convergence theorems for stochastic processes - in particular processes indexed by direct sets - and in sequential analysis. Applications of convergence theorems are seen in probability, analysis, and ergodic theory." "Almost everywhere, convergence and stochastic convergence of processes indexed by a directed set are studied, and solutions are given for problems left open in Krickeberg's theory for martingales and submartingales. The rewording of Vitali covering conditions in terms of stopping times establishes connections with the theory of stochastic processes and derivation. A study of martingales yields laws of large numbers for martingale differences, with application to "star-mixing" processes. Convergence of processes taking values in Banach spaces is related to geometric properties of these spaces. There is a self-contained section on operator ergodic theorems: the superadditive, Chacon-Ornstein, and Chacon theo