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In probability theory, Novikov's condition is the sufficient condition for a stochastic process which takes the form of the Radon-Nikodym derivative in Girsanov's theorem to be a martingale. If satisfied together with other conditions, Girsanov's theorem may be applied to a Brownian motion stochastic process to change from the original measure to the new measure defined by the Radon-Nikodym derivative. This condition was suggested and proved by Alexander Novikov. There are other results which may be used to show that the Radon-Nikodym derivative is a martingale, such as the more general criterion Kazamaki's condition, however Novikov's condition is the most well-known result. Assume that is a real valued adapted process on the probability space and is an adapted Brownian motion:〔Pascucci, Andrea (2011) ''PDE and Martingale Methods in Option Pricing''. Berlin: Springer-Verlag〕 If the condition : is fulfilled then the process : is a martingale under the probability measure and the filtration . Here denotes the Doléans-Dade exponential. ==References== Comments on Girsanov's Theorem by H. E. Krogstad, IMF 2003 () 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Novikov's condition」の詳細全文を読む スポンサード リンク
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