Finding a recursive formula for these probabilities in a semi-Markov chain












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For a semi-Markov chain, let $i,jin S$ where $S$ is the space of states. Let also $P=(p_{ij})_{i,jin S}$ be the matrix of transition probabilities. We define the following probabilities:
$e_{i,j}(n)=P(text{the chain enters state j at time n } |text{ the chain entered state i at time 0})$



and



$q_{i,j}(n)=P(text{the chain is at state j at time n }|text{ the chain entered state i at time 0})$.



I believe that it is almost obvious that $e_{i,j}(n)=sum_{kin S}q_{i,k}(n-1)p_{kj}$, hence $E(n)=Q(n-1)cdot P$, where $E(n)=(e_{i,j}(n))_{i,jin S}, Q(n)=(q_{i,j}(n))_{i,jin S}$. My intuition says that there is a recursive (with respect to $n$) formula for the probabilities $e_{i,j}(n)$ but I can't really formulate it. anyone has an idea?










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    1












    $begingroup$


    For a semi-Markov chain, let $i,jin S$ where $S$ is the space of states. Let also $P=(p_{ij})_{i,jin S}$ be the matrix of transition probabilities. We define the following probabilities:
    $e_{i,j}(n)=P(text{the chain enters state j at time n } |text{ the chain entered state i at time 0})$



    and



    $q_{i,j}(n)=P(text{the chain is at state j at time n }|text{ the chain entered state i at time 0})$.



    I believe that it is almost obvious that $e_{i,j}(n)=sum_{kin S}q_{i,k}(n-1)p_{kj}$, hence $E(n)=Q(n-1)cdot P$, where $E(n)=(e_{i,j}(n))_{i,jin S}, Q(n)=(q_{i,j}(n))_{i,jin S}$. My intuition says that there is a recursive (with respect to $n$) formula for the probabilities $e_{i,j}(n)$ but I can't really formulate it. anyone has an idea?










    share|cite|improve this question









    $endgroup$















      1












      1








      1





      $begingroup$


      For a semi-Markov chain, let $i,jin S$ where $S$ is the space of states. Let also $P=(p_{ij})_{i,jin S}$ be the matrix of transition probabilities. We define the following probabilities:
      $e_{i,j}(n)=P(text{the chain enters state j at time n } |text{ the chain entered state i at time 0})$



      and



      $q_{i,j}(n)=P(text{the chain is at state j at time n }|text{ the chain entered state i at time 0})$.



      I believe that it is almost obvious that $e_{i,j}(n)=sum_{kin S}q_{i,k}(n-1)p_{kj}$, hence $E(n)=Q(n-1)cdot P$, where $E(n)=(e_{i,j}(n))_{i,jin S}, Q(n)=(q_{i,j}(n))_{i,jin S}$. My intuition says that there is a recursive (with respect to $n$) formula for the probabilities $e_{i,j}(n)$ but I can't really formulate it. anyone has an idea?










      share|cite|improve this question









      $endgroup$




      For a semi-Markov chain, let $i,jin S$ where $S$ is the space of states. Let also $P=(p_{ij})_{i,jin S}$ be the matrix of transition probabilities. We define the following probabilities:
      $e_{i,j}(n)=P(text{the chain enters state j at time n } |text{ the chain entered state i at time 0})$



      and



      $q_{i,j}(n)=P(text{the chain is at state j at time n }|text{ the chain entered state i at time 0})$.



      I believe that it is almost obvious that $e_{i,j}(n)=sum_{kin S}q_{i,k}(n-1)p_{kj}$, hence $E(n)=Q(n-1)cdot P$, where $E(n)=(e_{i,j}(n))_{i,jin S}, Q(n)=(q_{i,j}(n))_{i,jin S}$. My intuition says that there is a recursive (with respect to $n$) formula for the probabilities $e_{i,j}(n)$ but I can't really formulate it. anyone has an idea?







      stochastic-processes markov-chains hidden-markov-models






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      asked Jan 14 at 17:08









      JustDroppedInJustDroppedIn

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