Approximation in probability












1












$begingroup$


To prove a CLT, I need first to prove that the following approximation holds



$$
sqrt{n}sum_{j=1}^nleft(left|int_{(j-1)/n}^{j/n}nu_s,dW_sright|,left|int_{j/n}^{(j+1)/n}nu_s,dW_sright|-nu_{(j-1)/n}^2,left|W_{j/n}-W_{(j-1)/n}right|,left|W_{(j+1)/n}-W_{j/n}right|,right)stackrel{p}{to} 0,quadtext{ as }nto+infty
$$

where $W$ is a Brownian motion independent from $nu$, which is an adapted continuous bounded stochastic process which has the property
$$
nu_{Delta} = nu_{0}+O_p(sqrt{Delta}),quadforallDelta>0.
$$



I have tried with the expansion (whose correctness is not so clear to me)



enter image description here



and also with the $L^2$-convergence. But, in both cases, I am able to prove only



$$
sum_{j=1}^nleft(left|int_{(j-1)/n}^{j/n}nu_s,dW_sright|,left|int_{j/n}^{(j+1)/n}nu_s,dW_sright|-nu_{(j-1)/n}^2,left|W_{j/n}-W_{(j-1)/n}right|,left|W_{(j+1)/n}-W_{j/n}right|,right)stackrel{p}{to} 0,quadtext{ as }nto+infty,
$$



i.e without the $sqrt{n}$ factor.










share|cite|improve this question









$endgroup$

















    1












    $begingroup$


    To prove a CLT, I need first to prove that the following approximation holds



    $$
    sqrt{n}sum_{j=1}^nleft(left|int_{(j-1)/n}^{j/n}nu_s,dW_sright|,left|int_{j/n}^{(j+1)/n}nu_s,dW_sright|-nu_{(j-1)/n}^2,left|W_{j/n}-W_{(j-1)/n}right|,left|W_{(j+1)/n}-W_{j/n}right|,right)stackrel{p}{to} 0,quadtext{ as }nto+infty
    $$

    where $W$ is a Brownian motion independent from $nu$, which is an adapted continuous bounded stochastic process which has the property
    $$
    nu_{Delta} = nu_{0}+O_p(sqrt{Delta}),quadforallDelta>0.
    $$



    I have tried with the expansion (whose correctness is not so clear to me)



    enter image description here



    and also with the $L^2$-convergence. But, in both cases, I am able to prove only



    $$
    sum_{j=1}^nleft(left|int_{(j-1)/n}^{j/n}nu_s,dW_sright|,left|int_{j/n}^{(j+1)/n}nu_s,dW_sright|-nu_{(j-1)/n}^2,left|W_{j/n}-W_{(j-1)/n}right|,left|W_{(j+1)/n}-W_{j/n}right|,right)stackrel{p}{to} 0,quadtext{ as }nto+infty,
    $$



    i.e without the $sqrt{n}$ factor.










    share|cite|improve this question









    $endgroup$















      1












      1








      1





      $begingroup$


      To prove a CLT, I need first to prove that the following approximation holds



      $$
      sqrt{n}sum_{j=1}^nleft(left|int_{(j-1)/n}^{j/n}nu_s,dW_sright|,left|int_{j/n}^{(j+1)/n}nu_s,dW_sright|-nu_{(j-1)/n}^2,left|W_{j/n}-W_{(j-1)/n}right|,left|W_{(j+1)/n}-W_{j/n}right|,right)stackrel{p}{to} 0,quadtext{ as }nto+infty
      $$

      where $W$ is a Brownian motion independent from $nu$, which is an adapted continuous bounded stochastic process which has the property
      $$
      nu_{Delta} = nu_{0}+O_p(sqrt{Delta}),quadforallDelta>0.
      $$



      I have tried with the expansion (whose correctness is not so clear to me)



      enter image description here



      and also with the $L^2$-convergence. But, in both cases, I am able to prove only



      $$
      sum_{j=1}^nleft(left|int_{(j-1)/n}^{j/n}nu_s,dW_sright|,left|int_{j/n}^{(j+1)/n}nu_s,dW_sright|-nu_{(j-1)/n}^2,left|W_{j/n}-W_{(j-1)/n}right|,left|W_{(j+1)/n}-W_{j/n}right|,right)stackrel{p}{to} 0,quadtext{ as }nto+infty,
      $$



      i.e without the $sqrt{n}$ factor.










      share|cite|improve this question









      $endgroup$




      To prove a CLT, I need first to prove that the following approximation holds



      $$
      sqrt{n}sum_{j=1}^nleft(left|int_{(j-1)/n}^{j/n}nu_s,dW_sright|,left|int_{j/n}^{(j+1)/n}nu_s,dW_sright|-nu_{(j-1)/n}^2,left|W_{j/n}-W_{(j-1)/n}right|,left|W_{(j+1)/n}-W_{j/n}right|,right)stackrel{p}{to} 0,quadtext{ as }nto+infty
      $$

      where $W$ is a Brownian motion independent from $nu$, which is an adapted continuous bounded stochastic process which has the property
      $$
      nu_{Delta} = nu_{0}+O_p(sqrt{Delta}),quadforallDelta>0.
      $$



      I have tried with the expansion (whose correctness is not so clear to me)



      enter image description here



      and also with the $L^2$-convergence. But, in both cases, I am able to prove only



      $$
      sum_{j=1}^nleft(left|int_{(j-1)/n}^{j/n}nu_s,dW_sright|,left|int_{j/n}^{(j+1)/n}nu_s,dW_sright|-nu_{(j-1)/n}^2,left|W_{j/n}-W_{(j-1)/n}right|,left|W_{(j+1)/n}-W_{j/n}right|,right)stackrel{p}{to} 0,quadtext{ as }nto+infty,
      $$



      i.e without the $sqrt{n}$ factor.







      stochastic-processes approximation-theory






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Jan 14 at 11:43









      AlmostSureUserAlmostSureUser

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