XIV: 06, 53-61, LNM 784 (1980)
AZÉMA, Jacques; GUNDY, Richard F.; YOR, Marc
Sur l'intégrabilité uniforme des martingales exponentielles (Martingale theory)
The main result of this paper is the following: Let $X$ be a martingale which is continuous and bounded in $L^1$ (both conditions are essential). Then $X$ is uniformly integrable if and only if $tP\{X^{*}>t\}$ or equivalently $tP\{S(X)>t\}$ tend to $0$ as $t\rightarrow\infty$, where $S(X)$ is the usual square function. The methods (using a good lambda inequality) are close to 1404
Comment: Generalized by Takaoka 3313
Keywords: Exponential martingales, Continuous martingales
Nature: Original
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