Proof of Feynman-Kac theorem












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I am reading a proof of Feynman-Kac theorem as done here, where I do not follow one step. Specifically, after the author derived:
$$dY_s = u_x(t-s, W_s)e^{-R(s)}dW_s$$
they seem to have concluded $$Y_t =u(0,W_t)e^{-R(t)}$$
in the next line. But the partial derivative in $x$ magically seemed to have disappeared.



Can anyone point out if this is a mistake or this is how it is supposed to be?










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    2














    I am reading a proof of Feynman-Kac theorem as done here, where I do not follow one step. Specifically, after the author derived:
    $$dY_s = u_x(t-s, W_s)e^{-R(s)}dW_s$$
    they seem to have concluded $$Y_t =u(0,W_t)e^{-R(t)}$$
    in the next line. But the partial derivative in $x$ magically seemed to have disappeared.



    Can anyone point out if this is a mistake or this is how it is supposed to be?










    share|cite|improve this question

























      2












      2








      2







      I am reading a proof of Feynman-Kac theorem as done here, where I do not follow one step. Specifically, after the author derived:
      $$dY_s = u_x(t-s, W_s)e^{-R(s)}dW_s$$
      they seem to have concluded $$Y_t =u(0,W_t)e^{-R(t)}$$
      in the next line. But the partial derivative in $x$ magically seemed to have disappeared.



      Can anyone point out if this is a mistake or this is how it is supposed to be?










      share|cite|improve this question













      I am reading a proof of Feynman-Kac theorem as done here, where I do not follow one step. Specifically, after the author derived:
      $$dY_s = u_x(t-s, W_s)e^{-R(s)}dW_s$$
      they seem to have concluded $$Y_t =u(0,W_t)e^{-R(t)}$$
      in the next line. But the partial derivative in $x$ magically seemed to have disappeared.



      Can anyone point out if this is a mistake or this is how it is supposed to be?







      probability-theory stochastic-processes brownian-motion






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      asked Nov 27 '18 at 1:41









      dezdichado

      6,1781929




      6,1781929






















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          It's a lot simpler than you thought. The definition of $Y_s$ is given in the beginning of the proof. He doesn't use the expression for $dY_s$ in any way in writing down $Y_t$.



          At the beginning he defines $Y_s=e^{-R(s)}u(t-s,W_s)$. Letting $s=t$ gives $Y_t=e^{-R(t)}u(0,W_t)$.






          share|cite|improve this answer





















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            It's a lot simpler than you thought. The definition of $Y_s$ is given in the beginning of the proof. He doesn't use the expression for $dY_s$ in any way in writing down $Y_t$.



            At the beginning he defines $Y_s=e^{-R(s)}u(t-s,W_s)$. Letting $s=t$ gives $Y_t=e^{-R(t)}u(0,W_t)$.






            share|cite|improve this answer


























              0














              It's a lot simpler than you thought. The definition of $Y_s$ is given in the beginning of the proof. He doesn't use the expression for $dY_s$ in any way in writing down $Y_t$.



              At the beginning he defines $Y_s=e^{-R(s)}u(t-s,W_s)$. Letting $s=t$ gives $Y_t=e^{-R(t)}u(0,W_t)$.






              share|cite|improve this answer
























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                0






                It's a lot simpler than you thought. The definition of $Y_s$ is given in the beginning of the proof. He doesn't use the expression for $dY_s$ in any way in writing down $Y_t$.



                At the beginning he defines $Y_s=e^{-R(s)}u(t-s,W_s)$. Letting $s=t$ gives $Y_t=e^{-R(t)}u(0,W_t)$.






                share|cite|improve this answer












                It's a lot simpler than you thought. The definition of $Y_s$ is given in the beginning of the proof. He doesn't use the expression for $dY_s$ in any way in writing down $Y_t$.



                At the beginning he defines $Y_s=e^{-R(s)}u(t-s,W_s)$. Letting $s=t$ gives $Y_t=e^{-R(t)}u(0,W_t)$.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Nov 27 '18 at 5:16









                Zachary Selk

                579311




                579311






























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