Power of stochastic kernel (transposition probability function)












0












$begingroup$


I am reading the following book:



Markov Chains and Invariant Probabilities, by Herndadez-Lerma and Lasserre (p.23)




  1. Given measure space $(X,mathcal{B})$


For each $xin X$ and $Bin mathcal{B}$, let $$P(x,B)=mathcal{P}(xi_{n+1}in B mid xi_n = x).$$ This defines a stochastic kernel on $X$, which means





  1. $P(x,cdot)$ is a probability measure on $mathcal{B}$ for each fixed $xin X$.


  2. $P(cdot,B)$ is a measurable function on $X$ for each fixed $Bin mathcal{B}$.


The $n-$step stochastic kernel $P^n(x,B)$ can be defined recursively by
$$P^n(x,B) = int_XP(x,dy)P^{n-1}(y,B) = int_XP^{n-1}(x,dy)P(y,B)$$



with $P^0(x,cdot) = delta_x(cdot)$.



Based on this definition,



$$P^1(x,B) = int_X P^0(x,dy)P(y,B) = int_x P(y,B)delta_x(dy) = P(x,B).$$



$$P^2(x,B) = int_X P^1(x,dy)P(y,B) = int_X P(y,B) int_X P(y,dy)delta_x(dy)$$



and then we have



$$P^2(x,B) = = int_X P(y,B) P(y,dy)delta_x(dy) = P(x,B) int_X P(y,dy)delta_x(dy)$$




I have no idea how to say $int_X P(y,dy)delta_x(dy) =P(x,B) $.



Moreover, can anyone let me know the meaning of such definition of $P^n(x,B)$ from the perspective of Markov Chain (this definition seems difficult to understand for me)?











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    0












    $begingroup$


    I am reading the following book:



    Markov Chains and Invariant Probabilities, by Herndadez-Lerma and Lasserre (p.23)




    1. Given measure space $(X,mathcal{B})$


    For each $xin X$ and $Bin mathcal{B}$, let $$P(x,B)=mathcal{P}(xi_{n+1}in B mid xi_n = x).$$ This defines a stochastic kernel on $X$, which means





    1. $P(x,cdot)$ is a probability measure on $mathcal{B}$ for each fixed $xin X$.


    2. $P(cdot,B)$ is a measurable function on $X$ for each fixed $Bin mathcal{B}$.


    The $n-$step stochastic kernel $P^n(x,B)$ can be defined recursively by
    $$P^n(x,B) = int_XP(x,dy)P^{n-1}(y,B) = int_XP^{n-1}(x,dy)P(y,B)$$



    with $P^0(x,cdot) = delta_x(cdot)$.



    Based on this definition,



    $$P^1(x,B) = int_X P^0(x,dy)P(y,B) = int_x P(y,B)delta_x(dy) = P(x,B).$$



    $$P^2(x,B) = int_X P^1(x,dy)P(y,B) = int_X P(y,B) int_X P(y,dy)delta_x(dy)$$



    and then we have



    $$P^2(x,B) = = int_X P(y,B) P(y,dy)delta_x(dy) = P(x,B) int_X P(y,dy)delta_x(dy)$$




    I have no idea how to say $int_X P(y,dy)delta_x(dy) =P(x,B) $.



    Moreover, can anyone let me know the meaning of such definition of $P^n(x,B)$ from the perspective of Markov Chain (this definition seems difficult to understand for me)?











    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      I am reading the following book:



      Markov Chains and Invariant Probabilities, by Herndadez-Lerma and Lasserre (p.23)




      1. Given measure space $(X,mathcal{B})$


      For each $xin X$ and $Bin mathcal{B}$, let $$P(x,B)=mathcal{P}(xi_{n+1}in B mid xi_n = x).$$ This defines a stochastic kernel on $X$, which means





      1. $P(x,cdot)$ is a probability measure on $mathcal{B}$ for each fixed $xin X$.


      2. $P(cdot,B)$ is a measurable function on $X$ for each fixed $Bin mathcal{B}$.


      The $n-$step stochastic kernel $P^n(x,B)$ can be defined recursively by
      $$P^n(x,B) = int_XP(x,dy)P^{n-1}(y,B) = int_XP^{n-1}(x,dy)P(y,B)$$



      with $P^0(x,cdot) = delta_x(cdot)$.



      Based on this definition,



      $$P^1(x,B) = int_X P^0(x,dy)P(y,B) = int_x P(y,B)delta_x(dy) = P(x,B).$$



      $$P^2(x,B) = int_X P^1(x,dy)P(y,B) = int_X P(y,B) int_X P(y,dy)delta_x(dy)$$



      and then we have



      $$P^2(x,B) = = int_X P(y,B) P(y,dy)delta_x(dy) = P(x,B) int_X P(y,dy)delta_x(dy)$$




      I have no idea how to say $int_X P(y,dy)delta_x(dy) =P(x,B) $.



      Moreover, can anyone let me know the meaning of such definition of $P^n(x,B)$ from the perspective of Markov Chain (this definition seems difficult to understand for me)?











      share|cite|improve this question











      $endgroup$




      I am reading the following book:



      Markov Chains and Invariant Probabilities, by Herndadez-Lerma and Lasserre (p.23)




      1. Given measure space $(X,mathcal{B})$


      For each $xin X$ and $Bin mathcal{B}$, let $$P(x,B)=mathcal{P}(xi_{n+1}in B mid xi_n = x).$$ This defines a stochastic kernel on $X$, which means





      1. $P(x,cdot)$ is a probability measure on $mathcal{B}$ for each fixed $xin X$.


      2. $P(cdot,B)$ is a measurable function on $X$ for each fixed $Bin mathcal{B}$.


      The $n-$step stochastic kernel $P^n(x,B)$ can be defined recursively by
      $$P^n(x,B) = int_XP(x,dy)P^{n-1}(y,B) = int_XP^{n-1}(x,dy)P(y,B)$$



      with $P^0(x,cdot) = delta_x(cdot)$.



      Based on this definition,



      $$P^1(x,B) = int_X P^0(x,dy)P(y,B) = int_x P(y,B)delta_x(dy) = P(x,B).$$



      $$P^2(x,B) = int_X P^1(x,dy)P(y,B) = int_X P(y,B) int_X P(y,dy)delta_x(dy)$$



      and then we have



      $$P^2(x,B) = = int_X P(y,B) P(y,dy)delta_x(dy) = P(x,B) int_X P(y,dy)delta_x(dy)$$




      I have no idea how to say $int_X P(y,dy)delta_x(dy) =P(x,B) $.



      Moreover, can anyone let me know the meaning of such definition of $P^n(x,B)$ from the perspective of Markov Chain (this definition seems difficult to understand for me)?








      probability-theory measure-theory markov-chains






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      edited Jan 9 at 21:54







      sleeve chen

















      asked Jan 9 at 9:50









      sleeve chensleeve chen

      3,08641852




      3,08641852






















          1 Answer
          1






          active

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          2












          $begingroup$

          $int f(y) ddelta_x(y)=f(x)$ for any non-negative measurable function $f$.



          $P^{n}(x,B)$ is the probability of starting at $x$ at time $0$ and landing inside $B$ in $n$ steps.
          You have made a mistake with $P^{2}(x,B)$. You should write $P^{2}(x,B)=int_X P^{1}(y,B) P^{1}(x,dy)$. It is not possible to pull out $P(x,B)$ from this.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Your first answer is what I used in deriving $P(x,B)$. Would you mind to give me more detailed comment about my derivation of $P^2(x,B)$?
            $endgroup$
            – sleeve chen
            Jan 9 at 10:09










          • $begingroup$
            Why can't I put out $P(x,B)$? The reason I do this is because $x$ and $B$ are not function of $y$. Is it not true?
            $endgroup$
            – sleeve chen
            Jan 9 at 10:54






          • 1




            $begingroup$
            In your formula for $P^{2}$ there should be a third variable $z$. You cannot have $dy$ appearing twice in that formula. You will not have $P(x,B)$ in that formula.
            $endgroup$
            – Kavi Rama Murthy
            Jan 9 at 11:48













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          1 Answer
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          1 Answer
          1






          active

          oldest

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          active

          oldest

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          active

          oldest

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          2












          $begingroup$

          $int f(y) ddelta_x(y)=f(x)$ for any non-negative measurable function $f$.



          $P^{n}(x,B)$ is the probability of starting at $x$ at time $0$ and landing inside $B$ in $n$ steps.
          You have made a mistake with $P^{2}(x,B)$. You should write $P^{2}(x,B)=int_X P^{1}(y,B) P^{1}(x,dy)$. It is not possible to pull out $P(x,B)$ from this.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Your first answer is what I used in deriving $P(x,B)$. Would you mind to give me more detailed comment about my derivation of $P^2(x,B)$?
            $endgroup$
            – sleeve chen
            Jan 9 at 10:09










          • $begingroup$
            Why can't I put out $P(x,B)$? The reason I do this is because $x$ and $B$ are not function of $y$. Is it not true?
            $endgroup$
            – sleeve chen
            Jan 9 at 10:54






          • 1




            $begingroup$
            In your formula for $P^{2}$ there should be a third variable $z$. You cannot have $dy$ appearing twice in that formula. You will not have $P(x,B)$ in that formula.
            $endgroup$
            – Kavi Rama Murthy
            Jan 9 at 11:48


















          2












          $begingroup$

          $int f(y) ddelta_x(y)=f(x)$ for any non-negative measurable function $f$.



          $P^{n}(x,B)$ is the probability of starting at $x$ at time $0$ and landing inside $B$ in $n$ steps.
          You have made a mistake with $P^{2}(x,B)$. You should write $P^{2}(x,B)=int_X P^{1}(y,B) P^{1}(x,dy)$. It is not possible to pull out $P(x,B)$ from this.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Your first answer is what I used in deriving $P(x,B)$. Would you mind to give me more detailed comment about my derivation of $P^2(x,B)$?
            $endgroup$
            – sleeve chen
            Jan 9 at 10:09










          • $begingroup$
            Why can't I put out $P(x,B)$? The reason I do this is because $x$ and $B$ are not function of $y$. Is it not true?
            $endgroup$
            – sleeve chen
            Jan 9 at 10:54






          • 1




            $begingroup$
            In your formula for $P^{2}$ there should be a third variable $z$. You cannot have $dy$ appearing twice in that formula. You will not have $P(x,B)$ in that formula.
            $endgroup$
            – Kavi Rama Murthy
            Jan 9 at 11:48
















          2












          2








          2





          $begingroup$

          $int f(y) ddelta_x(y)=f(x)$ for any non-negative measurable function $f$.



          $P^{n}(x,B)$ is the probability of starting at $x$ at time $0$ and landing inside $B$ in $n$ steps.
          You have made a mistake with $P^{2}(x,B)$. You should write $P^{2}(x,B)=int_X P^{1}(y,B) P^{1}(x,dy)$. It is not possible to pull out $P(x,B)$ from this.






          share|cite|improve this answer











          $endgroup$



          $int f(y) ddelta_x(y)=f(x)$ for any non-negative measurable function $f$.



          $P^{n}(x,B)$ is the probability of starting at $x$ at time $0$ and landing inside $B$ in $n$ steps.
          You have made a mistake with $P^{2}(x,B)$. You should write $P^{2}(x,B)=int_X P^{1}(y,B) P^{1}(x,dy)$. It is not possible to pull out $P(x,B)$ from this.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Jan 9 at 10:22

























          answered Jan 9 at 9:56









          Kavi Rama MurthyKavi Rama Murthy

          57.5k42160




          57.5k42160












          • $begingroup$
            Your first answer is what I used in deriving $P(x,B)$. Would you mind to give me more detailed comment about my derivation of $P^2(x,B)$?
            $endgroup$
            – sleeve chen
            Jan 9 at 10:09










          • $begingroup$
            Why can't I put out $P(x,B)$? The reason I do this is because $x$ and $B$ are not function of $y$. Is it not true?
            $endgroup$
            – sleeve chen
            Jan 9 at 10:54






          • 1




            $begingroup$
            In your formula for $P^{2}$ there should be a third variable $z$. You cannot have $dy$ appearing twice in that formula. You will not have $P(x,B)$ in that formula.
            $endgroup$
            – Kavi Rama Murthy
            Jan 9 at 11:48




















          • $begingroup$
            Your first answer is what I used in deriving $P(x,B)$. Would you mind to give me more detailed comment about my derivation of $P^2(x,B)$?
            $endgroup$
            – sleeve chen
            Jan 9 at 10:09










          • $begingroup$
            Why can't I put out $P(x,B)$? The reason I do this is because $x$ and $B$ are not function of $y$. Is it not true?
            $endgroup$
            – sleeve chen
            Jan 9 at 10:54






          • 1




            $begingroup$
            In your formula for $P^{2}$ there should be a third variable $z$. You cannot have $dy$ appearing twice in that formula. You will not have $P(x,B)$ in that formula.
            $endgroup$
            – Kavi Rama Murthy
            Jan 9 at 11:48


















          $begingroup$
          Your first answer is what I used in deriving $P(x,B)$. Would you mind to give me more detailed comment about my derivation of $P^2(x,B)$?
          $endgroup$
          – sleeve chen
          Jan 9 at 10:09




          $begingroup$
          Your first answer is what I used in deriving $P(x,B)$. Would you mind to give me more detailed comment about my derivation of $P^2(x,B)$?
          $endgroup$
          – sleeve chen
          Jan 9 at 10:09












          $begingroup$
          Why can't I put out $P(x,B)$? The reason I do this is because $x$ and $B$ are not function of $y$. Is it not true?
          $endgroup$
          – sleeve chen
          Jan 9 at 10:54




          $begingroup$
          Why can't I put out $P(x,B)$? The reason I do this is because $x$ and $B$ are not function of $y$. Is it not true?
          $endgroup$
          – sleeve chen
          Jan 9 at 10:54




          1




          1




          $begingroup$
          In your formula for $P^{2}$ there should be a third variable $z$. You cannot have $dy$ appearing twice in that formula. You will not have $P(x,B)$ in that formula.
          $endgroup$
          – Kavi Rama Murthy
          Jan 9 at 11:48






          $begingroup$
          In your formula for $P^{2}$ there should be a third variable $z$. You cannot have $dy$ appearing twice in that formula. You will not have $P(x,B)$ in that formula.
          $endgroup$
          – Kavi Rama Murthy
          Jan 9 at 11:48




















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