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Jul 19, 2012 at 19:55 comment added Jon @GeorgeLowther: You got it! It is a Fokker-Planck equation I would like to see and I was not able to read from standard literature. Please, put it as an answer and I will accept it. Thanks a lot!
Jul 19, 2012 at 18:16 comment added George Lowther I mean, at zero (not time 0).
Jul 19, 2012 at 18:15 comment added George Lowther @Jon: I don't understand what you mean, what does "exist a kind of diffusion equation" mean? Do you mean a backwards equation/Fokker-Planck equation. There does, but it's a little different from the backward equations you get with smooth diffusion coefficient, as you have to enforce continuity of the derivative at time 0.
Jul 19, 2012 at 10:52 comment added Jon @George Lowther: Thanks, but the question is, does it exist a kind of diffusion equation also in this case?
Jul 19, 2012 at 10:37 comment added George Lowther Your SDE will have a unique weak solution which is a one dimensional diffusion with speed measure $(a{\rm sgn}(x)+b)^{-2}dx$ (as long as ${\rm sgn}(0)$ is defined appropriately).
Jul 18, 2012 at 9:48 history edited Jon CC BY-SA 3.0
Fixed a mistake
Jul 18, 2012 at 9:48 comment added Jon @Didier Piau: Thanks, I will fix this.
Jul 18, 2012 at 8:48 comment added Did @TheBridge is right, naturally: sign(X) is not sign(W).
Jun 13, 2012 at 16:37 comment added Jon @The Bridge: There is such a big difference that I cannot see it and this is not the remark by Ilya at all. As you can note, if I take the two constants to be $a=1$ and $b=0$ you are back to Tanaka sde otherwise it is just the sum of a Tanaka plus a normal Wiener.
Jun 13, 2012 at 15:55 comment added The Bridge @ Jon : a remark as noted by Ilya, your sde is not Tanaka's sde, the right equation is $dX_t=sign(X_t)dW_t$. Best regards.
Jan 27, 2012 at 13:25 comment added Jon @Ilya: Thank you. Indeed, it was difficult to identify the very nature of this process.
Jan 27, 2012 at 12:22 comment added SBF Well, it's not quite an SDE in the sense that the right-hand side does not depend on $X$, so you can write the explicit solution $$ X_t = X_0+\int\limits_0^t[a\sign W_s +b ]\mathrm dW_s. $$ On the other hand, the Kolmogorov equation is defined only for Markov processes, I guess. I am not sure that the process $X$ is Markov.
Jan 19, 2012 at 9:42 history asked Jon CC BY-SA 3.0