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Thread: Transition Probability

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    Transition Probability



    Hi.
    I have a question about transition probability.
    Q) Markov chain on states {0,1,2,3,4,5} has transition probability matrix (which is 6 by 6 matrix).
    okay, the matrix given, but I won't write it here.
    1) Find all classes from this matrix.
    2) Find lim (n goes to infinity) P^n_{5i} for i = 0,1,2,3,4,5
    I have no idea about 1)
    for 2), I learned from the class that lim (n goes to infinity) P^n_{ij} = pi_{j} = sigma (i=0 to infinity) pi_{i}P_{ij} and sigma (i=0 to infinity) pi_{i} = 1

    so since lim (n goes to infinity) P^n_{5i} is equal to pi_{i}, and this equals to sigma (i=0 to 5) pi_{i}P_{5i}

    so using sigma (i=0 to 5) pi_{i}P_{5i} and it is given that sigma (i=0 to infinity) pi_{i} = 1,

    so pi_{i} = P_{5i} the answer will be 1/6
    (in the last row, all the probabilities are evenly 1/6)

    please give me the hint or idea about how to do for 1)
    and check for 2).
    Thank you...

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    Re: Transition Probability

    he means transient classes and positive recurrent in 1 and in 2 meybe you should find the stationary distribution before answering. But i assume you do are not familiar with what i said, right?

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    Re: Transition Probability

    yes...I am not sure...
    the prof went through this part really fast without any example...
    so I thought I understood the concept and the theorem, but I do not know
    how to apply this to actual example...
    He said this prob is really easy...I should have done within 5 min...
    Isn't the stationary distribution {pi_{i}} i = 0 to infinity?

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    Re: Transition Probability

    the stationary distribtution π is the one that solves this
    π=πP. Can you upload the matrix?

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    Re: Transition Probability

    I don't know how to upload matrix, so
    1/3 2/3 0 0 0 0
    2/3 1/3 0 0 0 0
    0 0 1/4 3/4 0 0
    0 0 1/5 4/5 0 0
    1/4 0 1/4 0 1/4 1/4
    1/6 1/6 1/6 1/6 1/6 1/6

    this is the matrix which is given...
    and isn't the {1,2} and {3,4} are sets containing recurrent states?

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    Re: Transition Probability

    yes they are. you are right and they are irreducible. 5 and 6 are trnasient. Now there is no unique stationary distribution. So you want lim_{n goes to inifnity} P_{5i} for i=1,2,3,4,5,6. Well you can use the diagonalization theorem to find P_{5i} for beginning and then apply the limit

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    Re: Transition Probability

    so I tried with
    when i = 0, f_{50}^n = P_{50} when n = 1 and
    = P_{51}P_{11}^{n-2}P_{10} when n >= 2
    so this equal to = 1/6 + sigma(n = 2 to infinity) n(1/6)((1/3)^(n-2))(2/3)
    so if you work out this, I get 4/9 (I just followed how my prof. did in class)

    when i = 1, f_{51}^n = P_{51} when n = 1 and
    = P_{52}P_{22}^{n-2}P_{21} when n >= 2
    since P_{21} is zero, it is equal to 1/6

    when i = 3 and i = 5, I get 1/6

    when i = 2, f_{52}^n = P_{52} when n = 1 and
    = P_{53}P_{33}^{n-2}P_{32} when n >= 2
    so this equal to = 1/6 + sigma(n = 2 to infinity) n(1/6)((4/5)^(n-2))(1/5)
    so if you work out this, I get 7/40

    when i = 4, f_{54}^n = P_{54} when n = 1 and
    = P_{55}P_{54}^{n-1} when n >= 1
    so I work out this, I get 2/9

    and since lim(n goes to infinity) P_{5i}^n = 1/(sigma(n=0 to 5) nf_{ii}^n) = 120/161

    this sounds crazy...but I just tried...
    I don't know this is right or not...
    I have to do this by tomorrow...can you tell me something really close to answer?
    Thank you...
    Bye...

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    Re: Transition Probability


    I agree with the rationale for the f caculations. but i do not agree that f_{50}=P_{50}^{n=1}.
    I think states 2, 3 amd 4 and 5 are transient. thus the answer is zero for them. P_{50} and P_{51} are not zero.

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