Good-lambda bound for Brownian stopping time and maximum
ID: good-lambda-bound-for-brownian-stopping-time-and-maximum
For Brownian motion started at zero, condition at time . If the stopping time exceeds while the running absolute maximum stays below , the path must remain in a fixed interval for another time units. Its expected exit time from this interval is at most . Markov's inequality yields the displayed bound. Integrating it against for a function of moderate growth, then absorbing the small tail term, proves .
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