An Extension of Kazamaki's Results on BMO Differentials
Protter, Philip
Ann. Probab., Tome 8 (1980) no. 6, p. 1107-1118 / Harvested from Project Euclid
Kazamaki has shown that if $(M^n)_{n\geqq 1}, M$ are BMO martingales with continuous paths and $\lim M^n = M$ in BMO, then $\mathscr{E}(M^n)$ converges in $\mathscr{H}^1$ to $\mathscr{E}(M)$, where $\mathscr{E}(M)$ denotes the stochastic exponential of $M$. While Kazamaki's result does not extend to the right continuous case, it does extend "locally." It is shown here that if $M^n, M$ are semimartingales and $M^n$ converges locally in $\mathscr{H}^\omega$ (a semimartingale BMO-type norm) to $M$ then $X^n$ converges locally in $\mathscr{H}^p (1 \leqq p < \infty)$ to $X$, where $X^n, X$ are respectively solutions of stochastic integral equations with Lipschitz-type coefficients and differentials $dM^n, dM$. (The coefficients are also allowed to vary.) This is a stronger stability than usually holds for solutions of stochastic integral equations, reflecting the strength of the $\mathscr{H}^\omega$ norm.
Publié le : 1980-12-14
Classification:  Stochastic differential equations,  BMO,  martingales,  semimartingales,  60H10,  60H20,  60G45
@article{1176994572,
     author = {Protter, Philip},
     title = {An Extension of Kazamaki's Results on BMO Differentials},
     journal = {Ann. Probab.},
     volume = {8},
     number = {6},
     year = {1980},
     pages = { 1107-1118},
     language = {en},
     url = {http://dml.mathdoc.fr/item/1176994572}
}
Protter, Philip. An Extension of Kazamaki's Results on BMO Differentials. Ann. Probab., Tome 8 (1980) no. 6, pp.  1107-1118. http://gdmltest.u-ga.fr/item/1176994572/