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Carthaginian enlargement of filtrations

Published online by Cambridge University Press:  01 August 2013

Giorgia Callegaro
Affiliation:
Scuola Normale Superiore di Pisa, Piazza dei Cavalieri, 7 56126 Pisa, Italy. giogiocallegaro@gmail.com CREST, 15 Boulevard Gabriel Péri, 92254 Malakoff Cedex, France
Monique Jeanblanc
Affiliation:
Institut Europlace de Finance (EIF), Palais Brongniart, 28 Place de la Bourse, 75002 Paris, France; monique.jeanblanc@univ-evry.fr
Behnaz Zargari
Affiliation:
Sharif University of Technology, P.O. Box 11365-8639, Tehran, Iran; behnazzargari@yahoo.com
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Abstract

This work is concerned with the theory of initial and progressive enlargements of areference filtration \hbox{$\mathbb{F}$}F with a random time τ. We provide, under anequivalence assumption, slightly stronger than the absolute continuity assumption ofJacod, alternative proofs to results concerning canonical decomposition of an \hbox{$\mathbb{F}$}F-martingalein the enlarged filtrations. Also, we address martingales’ characterization in theenlarged filtrations in terms of martingales in the reference filtration, as well aspredictable representation theorems in the enlarged filtrations.

Type
Research Article
Copyright
© EDP Sciences, SMAI, 2013

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