An explicit Skorokhod embedding for the age of Brownian excursions and Azema martingale

A general methodology allowing to solve the Skorokhod stopping problem for positive functionals of Brownian excursions, with the help of Brownian local time, is developed. The stopping times we consider have the following form: Tμ=inf{t>0: Ft≥μF(Lt)}. As an application, the Skorokhod embeddin...

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Bibliographic Details
Main Authors: Obloj, J, Yor, M
Format: Journal article
Language:English
Published: 2004
Description
Summary:A general methodology allowing to solve the Skorokhod stopping problem for positive functionals of Brownian excursions, with the help of Brownian local time, is developed. The stopping times we consider have the following form: Tμ=inf{t>0: Ft≥μF(Lt)}. As an application, the Skorokhod embedding problem for a number of functionals (Ft: t≥0), including the age (length) and the maximum (height) of excursions, is solved. Explicit formulae for the corresponding stopping times Tμ, such that FTμ∼μ, are given. It is shown that the function μF is the same for the maximum and for the age, μ=ψ μ-1, where ψμ(x) =∫[0,x](y/μ̄(y)) dμ(y). The joint law of (gTμ,Tμ, LTμ), in the case of the age functional, is characterized. Examples for specific measures μ are discussed. Finally, a randomized solution to the embedding problem for Azéma martingale is deduced. Throughout the article, two possible approaches, using excursions and martingale theories, are presented in parallel. © 2003 Elsevier B.V. All rights reserved.