Question about proof with doubly stochastic matrix. Why do we need the uniqueness of $pi_j?$












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A stochastic matrix is called doubly stochastic if its rows and
columns sum to 1. Show that a Markov chain whose transition matrix is
doubly stochastic has a stationary distribution, which is uniform on
the statespace.




I'm trying to under stand the related problem but I don't understand how the uniqueness theorem comes in in the first row of the accepted answer, shouldm't it be $pi_i$? What do those sums even mean? They don't have any upper bound but i suppose the upper bound should be the upper bound of the statespace?










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    0












    $begingroup$



    A stochastic matrix is called doubly stochastic if its rows and
    columns sum to 1. Show that a Markov chain whose transition matrix is
    doubly stochastic has a stationary distribution, which is uniform on
    the statespace.




    I'm trying to under stand the related problem but I don't understand how the uniqueness theorem comes in in the first row of the accepted answer, shouldm't it be $pi_i$? What do those sums even mean? They don't have any upper bound but i suppose the upper bound should be the upper bound of the statespace?










    share|cite|improve this question









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      0












      0








      0





      $begingroup$



      A stochastic matrix is called doubly stochastic if its rows and
      columns sum to 1. Show that a Markov chain whose transition matrix is
      doubly stochastic has a stationary distribution, which is uniform on
      the statespace.




      I'm trying to under stand the related problem but I don't understand how the uniqueness theorem comes in in the first row of the accepted answer, shouldm't it be $pi_i$? What do those sums even mean? They don't have any upper bound but i suppose the upper bound should be the upper bound of the statespace?










      share|cite|improve this question









      $endgroup$





      A stochastic matrix is called doubly stochastic if its rows and
      columns sum to 1. Show that a Markov chain whose transition matrix is
      doubly stochastic has a stationary distribution, which is uniform on
      the statespace.




      I'm trying to under stand the related problem but I don't understand how the uniqueness theorem comes in in the first row of the accepted answer, shouldm't it be $pi_i$? What do those sums even mean? They don't have any upper bound but i suppose the upper bound should be the upper bound of the statespace?







      markov-chains






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      asked Dec 27 '18 at 16:53









      ParsevalParseval

      3,0741719




      3,0741719






















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          They're using the uniqueness theorem so that, when they show that the uniform distribution is a valid stationary distribution for the doubly stochastic transition matrix, it must be the stationary distribution.



          The uniqueness of the stationary distribution comes directly out of the irreducibility of $P$ + aperiodicity of $P$ + finite state space of the system, and the sums are just matrix multiplications over the state space (from $i=0$ to $M$).






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            1 Answer
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            $begingroup$

            They're using the uniqueness theorem so that, when they show that the uniform distribution is a valid stationary distribution for the doubly stochastic transition matrix, it must be the stationary distribution.



            The uniqueness of the stationary distribution comes directly out of the irreducibility of $P$ + aperiodicity of $P$ + finite state space of the system, and the sums are just matrix multiplications over the state space (from $i=0$ to $M$).






            share|cite|improve this answer









            $endgroup$


















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              $begingroup$

              They're using the uniqueness theorem so that, when they show that the uniform distribution is a valid stationary distribution for the doubly stochastic transition matrix, it must be the stationary distribution.



              The uniqueness of the stationary distribution comes directly out of the irreducibility of $P$ + aperiodicity of $P$ + finite state space of the system, and the sums are just matrix multiplications over the state space (from $i=0$ to $M$).






              share|cite|improve this answer









              $endgroup$
















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                1





                $begingroup$

                They're using the uniqueness theorem so that, when they show that the uniform distribution is a valid stationary distribution for the doubly stochastic transition matrix, it must be the stationary distribution.



                The uniqueness of the stationary distribution comes directly out of the irreducibility of $P$ + aperiodicity of $P$ + finite state space of the system, and the sums are just matrix multiplications over the state space (from $i=0$ to $M$).






                share|cite|improve this answer









                $endgroup$



                They're using the uniqueness theorem so that, when they show that the uniform distribution is a valid stationary distribution for the doubly stochastic transition matrix, it must be the stationary distribution.



                The uniqueness of the stationary distribution comes directly out of the irreducibility of $P$ + aperiodicity of $P$ + finite state space of the system, and the sums are just matrix multiplications over the state space (from $i=0$ to $M$).







                share|cite|improve this answer












                share|cite|improve this answer



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                answered Dec 28 '18 at 1:05









                aghostinthefiguresaghostinthefigures

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                1,2891217






























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