随机过程求助 proof of continuous local martingal with finite variantion is constant

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查看11 | 回复1 | 2011-2-9 13:01:22 | 显示全部楼层 |阅读模式
thank you for your answer, but we start with local martingal and dont have all martingal properties.
E[X_t-X_s]=0 for some stopping time, which u did not consider.
"V[s,t]=int|X_u| du< Infinity implies int (X_u)du < Infinity" for every finite interval P.a.s is given, but what do you mean by X'_u, how is it definded?
E[X_t-X_s]=E int (X'_u) du, why ist that true?
stoch process does not have nessecarilly a derivative, you mean increment?

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千问 | 2011-2-9 13:01:22 | 显示全部楼层
Given the probability space, (Omega, P, F)we need to prove: E[X_t|F_s]=X_s that is E[X_t-X_s+ X_s|F_s]= E[X_t-X_s|F_s]+ X_s= E[X_t-X_s]+X_snamely, E[X_t-X_s]=0;Since X is the process of finite variation. let V be the variation:V[s,t]=int|X'_u| du< Infinity implies int (X'_u)du < Infinity0=E[X_t-X_s]=E int (X'_u) du=
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