Kazamaki's condition

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In mathematics Kazamaki's condition gives a sufficient criterion ensuring that the Doléans-Dade exponential of a local martingale is a true martingale. This is particularly important if Girsanov's theorem is to be applied to perform a change of measure. Kazamaki's condition is more general than Novikov's condition.

Statement of Kazamaki's condition[edit]

Let M = (M_t)_{t \ge 0} be a continuous local martingale with respect to a right-continuous filtration (\mathcal{F}_t)_{t \ge 0}. If (\exp(M_t/2))_{t \ge 0} is a uniformly integrable submartingale, then the Doléans-Dade exponential Ɛ(M) of M is a uniformly integrable martingale.

References[edit]

  • Daniel Revuz, Marc Yor: Continuous Martingales and Brownian motion. Springer-Verlag, New York 1999, ISBN 3-540-64325-7.