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On wald-type optimal stopping for Brownian motion

Published online by Cambridge University Press:  14 July 2016

S. E. Graversen*
Affiliation:
University of Aarhus
G. Peškir*
Affiliation:
University of Aarhus
*
Postal address: Institute of Mathematics, University of Aarhus, Ny Munkegade, 8000 Aarhus, Denmark.
∗∗Postal address: Institute of Mathematics, University of Aarhus, Ny Munkegade, 8000 Aarhus, Denmark. Also at: Department of Mathematics, University of Zagreb, Bijenička 30, 41000 Zagreb, Croatia.

Abstract

The solution is presented to all optimal stopping problems of the form supτE(G(|Β τ |) – cτ), where is standard Brownian motion and the supremum is taken over all stopping times τ for B with finite expectation, while the map G :+ → ℝ satisfies for some being given and fixed. The optimal stopping time is shown to be the hitting time by the reflecting Brownian motion of the set of all (approximate) maximum points of the map . The method of proof relies upon Wald's identity for Brownian motion and simple real analysis arguments. A simple proof of the Dubins–Jacka–Schwarz–Shepp–Shiryaev (square root of two) maximal inequality for randomly stopped Brownian motion is given as an application.

Type
Research Papers
Copyright
Copyright © Applied Probability Trust 1997 

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