Probability and expected number of steps of/from a transient to an absorbing state in a Markov Chain
$begingroup$
Given an arbitrary but relatively large (more than 50 states) transition matrix, the goal is to find the answer to the following problem:
Assuming we start at state A and ultimately end up in (the only)
absorbing state Z we are looking for a state S that follows:
A → [m steps] → S → [n steps] → Z
How can I calculate the probability of reaching S before reaching Z and the corresponding expected number of steps (n) from S to Z?
Update 24-12:
So I guess the first part is mosre doable than i thought (if my reasoning is correct). My approach:
Rearrange the matrix in canonical form:
$P = left[begin{matrix}
Q & R \ mathbf{0} & I
end{matrix}right]$
Find the fundamental matrix:
$ N = (I - Q)^{-1} $
Find the transient probabilities:
$ H = (N - I)N_{dg} $
And the row of H which corresponds to starting state A. The entries in this row vector should correspond to the probabilities of reaching A before reaching Z.
** Is my thinking here correct? And how can I condition the original transition matrix P to estimate the steps (n) between A and Z? **
markov-chains conditional-probability
$endgroup$
add a comment |
$begingroup$
Given an arbitrary but relatively large (more than 50 states) transition matrix, the goal is to find the answer to the following problem:
Assuming we start at state A and ultimately end up in (the only)
absorbing state Z we are looking for a state S that follows:
A → [m steps] → S → [n steps] → Z
How can I calculate the probability of reaching S before reaching Z and the corresponding expected number of steps (n) from S to Z?
Update 24-12:
So I guess the first part is mosre doable than i thought (if my reasoning is correct). My approach:
Rearrange the matrix in canonical form:
$P = left[begin{matrix}
Q & R \ mathbf{0} & I
end{matrix}right]$
Find the fundamental matrix:
$ N = (I - Q)^{-1} $
Find the transient probabilities:
$ H = (N - I)N_{dg} $
And the row of H which corresponds to starting state A. The entries in this row vector should correspond to the probabilities of reaching A before reaching Z.
** Is my thinking here correct? And how can I condition the original transition matrix P to estimate the steps (n) between A and Z? **
markov-chains conditional-probability
$endgroup$
$begingroup$
To clarify, we have a starting state A, ending state Z, and want to find a state S such that, conditioned on passing through S, the expected value of the number of steps to get to S is m, the the number of steps to get to Z is n?
$endgroup$
– Alex
Dec 23 '18 at 3:10
$begingroup$
Yes, exactly! I just don't exactly how to approach such calculation.
$endgroup$
– Remy Kabel
Dec 23 '18 at 11:00
$begingroup$
My idea would be that this problem is two-fold: 1. Find the probability of reaching S before absorption, and then 2. Transforming the matrix to the conditional probability as you say. But honestly I don't know exactly how to approach either.
$endgroup$
– Remy Kabel
Dec 23 '18 at 11:06
$begingroup$
Are you looking for the probability distribution of the time to absorption for finite discrete or continuous time Markov chain?
$endgroup$
– Waqas
Dec 28 '18 at 12:31
add a comment |
$begingroup$
Given an arbitrary but relatively large (more than 50 states) transition matrix, the goal is to find the answer to the following problem:
Assuming we start at state A and ultimately end up in (the only)
absorbing state Z we are looking for a state S that follows:
A → [m steps] → S → [n steps] → Z
How can I calculate the probability of reaching S before reaching Z and the corresponding expected number of steps (n) from S to Z?
Update 24-12:
So I guess the first part is mosre doable than i thought (if my reasoning is correct). My approach:
Rearrange the matrix in canonical form:
$P = left[begin{matrix}
Q & R \ mathbf{0} & I
end{matrix}right]$
Find the fundamental matrix:
$ N = (I - Q)^{-1} $
Find the transient probabilities:
$ H = (N - I)N_{dg} $
And the row of H which corresponds to starting state A. The entries in this row vector should correspond to the probabilities of reaching A before reaching Z.
** Is my thinking here correct? And how can I condition the original transition matrix P to estimate the steps (n) between A and Z? **
markov-chains conditional-probability
$endgroup$
Given an arbitrary but relatively large (more than 50 states) transition matrix, the goal is to find the answer to the following problem:
Assuming we start at state A and ultimately end up in (the only)
absorbing state Z we are looking for a state S that follows:
A → [m steps] → S → [n steps] → Z
How can I calculate the probability of reaching S before reaching Z and the corresponding expected number of steps (n) from S to Z?
Update 24-12:
So I guess the first part is mosre doable than i thought (if my reasoning is correct). My approach:
Rearrange the matrix in canonical form:
$P = left[begin{matrix}
Q & R \ mathbf{0} & I
end{matrix}right]$
Find the fundamental matrix:
$ N = (I - Q)^{-1} $
Find the transient probabilities:
$ H = (N - I)N_{dg} $
And the row of H which corresponds to starting state A. The entries in this row vector should correspond to the probabilities of reaching A before reaching Z.
** Is my thinking here correct? And how can I condition the original transition matrix P to estimate the steps (n) between A and Z? **
markov-chains conditional-probability
markov-chains conditional-probability
edited Dec 24 '18 at 22:19
Remy Kabel
asked Dec 19 '18 at 8:45
Remy KabelRemy Kabel
735
735
$begingroup$
To clarify, we have a starting state A, ending state Z, and want to find a state S such that, conditioned on passing through S, the expected value of the number of steps to get to S is m, the the number of steps to get to Z is n?
$endgroup$
– Alex
Dec 23 '18 at 3:10
$begingroup$
Yes, exactly! I just don't exactly how to approach such calculation.
$endgroup$
– Remy Kabel
Dec 23 '18 at 11:00
$begingroup$
My idea would be that this problem is two-fold: 1. Find the probability of reaching S before absorption, and then 2. Transforming the matrix to the conditional probability as you say. But honestly I don't know exactly how to approach either.
$endgroup$
– Remy Kabel
Dec 23 '18 at 11:06
$begingroup$
Are you looking for the probability distribution of the time to absorption for finite discrete or continuous time Markov chain?
$endgroup$
– Waqas
Dec 28 '18 at 12:31
add a comment |
$begingroup$
To clarify, we have a starting state A, ending state Z, and want to find a state S such that, conditioned on passing through S, the expected value of the number of steps to get to S is m, the the number of steps to get to Z is n?
$endgroup$
– Alex
Dec 23 '18 at 3:10
$begingroup$
Yes, exactly! I just don't exactly how to approach such calculation.
$endgroup$
– Remy Kabel
Dec 23 '18 at 11:00
$begingroup$
My idea would be that this problem is two-fold: 1. Find the probability of reaching S before absorption, and then 2. Transforming the matrix to the conditional probability as you say. But honestly I don't know exactly how to approach either.
$endgroup$
– Remy Kabel
Dec 23 '18 at 11:06
$begingroup$
Are you looking for the probability distribution of the time to absorption for finite discrete or continuous time Markov chain?
$endgroup$
– Waqas
Dec 28 '18 at 12:31
$begingroup$
To clarify, we have a starting state A, ending state Z, and want to find a state S such that, conditioned on passing through S, the expected value of the number of steps to get to S is m, the the number of steps to get to Z is n?
$endgroup$
– Alex
Dec 23 '18 at 3:10
$begingroup$
To clarify, we have a starting state A, ending state Z, and want to find a state S such that, conditioned on passing through S, the expected value of the number of steps to get to S is m, the the number of steps to get to Z is n?
$endgroup$
– Alex
Dec 23 '18 at 3:10
$begingroup$
Yes, exactly! I just don't exactly how to approach such calculation.
$endgroup$
– Remy Kabel
Dec 23 '18 at 11:00
$begingroup$
Yes, exactly! I just don't exactly how to approach such calculation.
$endgroup$
– Remy Kabel
Dec 23 '18 at 11:00
$begingroup$
My idea would be that this problem is two-fold: 1. Find the probability of reaching S before absorption, and then 2. Transforming the matrix to the conditional probability as you say. But honestly I don't know exactly how to approach either.
$endgroup$
– Remy Kabel
Dec 23 '18 at 11:06
$begingroup$
My idea would be that this problem is two-fold: 1. Find the probability of reaching S before absorption, and then 2. Transforming the matrix to the conditional probability as you say. But honestly I don't know exactly how to approach either.
$endgroup$
– Remy Kabel
Dec 23 '18 at 11:06
$begingroup$
Are you looking for the probability distribution of the time to absorption for finite discrete or continuous time Markov chain?
$endgroup$
– Waqas
Dec 28 '18 at 12:31
$begingroup$
Are you looking for the probability distribution of the time to absorption for finite discrete or continuous time Markov chain?
$endgroup$
– Waqas
Dec 28 '18 at 12:31
add a comment |
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$begingroup$
To clarify, we have a starting state A, ending state Z, and want to find a state S such that, conditioned on passing through S, the expected value of the number of steps to get to S is m, the the number of steps to get to Z is n?
$endgroup$
– Alex
Dec 23 '18 at 3:10
$begingroup$
Yes, exactly! I just don't exactly how to approach such calculation.
$endgroup$
– Remy Kabel
Dec 23 '18 at 11:00
$begingroup$
My idea would be that this problem is two-fold: 1. Find the probability of reaching S before absorption, and then 2. Transforming the matrix to the conditional probability as you say. But honestly I don't know exactly how to approach either.
$endgroup$
– Remy Kabel
Dec 23 '18 at 11:06
$begingroup$
Are you looking for the probability distribution of the time to absorption for finite discrete or continuous time Markov chain?
$endgroup$
– Waqas
Dec 28 '18 at 12:31