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Conditioned stable Lévy processes and the Lamperti representation

Published online by Cambridge University Press:  14 July 2016

M. E. Caballero*
Affiliation:
Universidad Nacional Autónoma de México
L. Chaumont*
Affiliation:
Université Pierre et Marie Curie
*
Postal address: Instituto de Matemáticas, Universidad Nacional Autónoma de México, Mexico 04510 DF. Email address: emilia@servidor.unam.mx
∗∗Postal address: Laboratoire de Probabilités et Modèles Aléatoires, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France. Email address: chaumont@ccr.jussieu.fr
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Abstract

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By variously killing a stable Lévy process when it leaves the positive half-line, conditioning it to stay positive, and conditioning it to hit 0 continuously, we obtain three different, positive, self-similar Markov processes which illustrate the three classes described by Lamperti (1972). For each of these processes, we explicitly compute the infinitesimal generator and from this deduce the characteristics of the underlying Lévy process in the Lamperti representation. The proof of this result bears on the behaviour at time 0 of stable Lévy processes before their first passage time across level 0, which we describe here. As an application, for a certain class of Lévy processes we give the law of the minimum before an independent exponential time. This provides the explicit form of the spatial Wiener-Hopf factor at a particular point and the value of the ruin probability for this class of Lévy processes.

Type
Research Papers
Copyright
© Applied Probability Trust 2006 

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