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On Approximations of Small Jumps of Subordinators with Particular Emphasis on a Dickman-Type Limit

Published online by Cambridge University Press:  14 July 2016

Shai Covo*
Affiliation:
Bar Ilan University
*
Postal address: Department of Mathematics, Bar Ilan University, 52900 Ramat-Gan, Israel. Email address: green355@netvision.net.il
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Abstract

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Let X be a pure-jump subordinator (i.e. nondecreasing Lévy process with no drift) with infinite Lévy measure, let Xε be the sum of jumps not exceeding ε, and let µ(ε)=E[Xε(1)]. We study the question of weak convergence of Xε/µ(ε) as ε ↓0, in terms of the limit behavior of µ(ε)/ε. The most interesting case reduces to the weak convergence of Xε/ε to a subordinator whose marginals are generalized Dickman distributions; we give some necessary and sufficient conditions for this to hold. For a certain significant class of subordinators for which the latter convergence holds, and whose most prominent representative is the gamma process, we give some detailed analysis regarding the convergence quality (in particular, in the context of approximating X itself). This paper completes, in some respects, the study made by Asmussen and Rosiński (2001).

Type
Research Article
Copyright
Copyright © Applied Probability Trust 2009 

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