Find the period of a state in a Markov chain

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Let $X_n:n=0,1,2,ldots$ be a Markov chain with transition probabilities as given below:

Determine the period of each state.
The answer is "The only state with period $> 1$ is $1$, which has period $3$. I don't understand why other states like $2$, $3$, $5$, $6$ are not with period $3$, they can also take $3$ steps back to themselves, can't them?
stochastic-processes markov-chains
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Let $X_n:n=0,1,2,ldots$ be a Markov chain with transition probabilities as given below:

Determine the period of each state.
The answer is "The only state with period $> 1$ is $1$, which has period $3$. I don't understand why other states like $2$, $3$, $5$, $6$ are not with period $3$, they can also take $3$ steps back to themselves, can't them?
stochastic-processes markov-chains
2
You're right. All states except state $4$ takes $3n$ steps back to itself.
â GNU Supporter
Dec 13 '15 at 12:17
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
Let $X_n:n=0,1,2,ldots$ be a Markov chain with transition probabilities as given below:

Determine the period of each state.
The answer is "The only state with period $> 1$ is $1$, which has period $3$. I don't understand why other states like $2$, $3$, $5$, $6$ are not with period $3$, they can also take $3$ steps back to themselves, can't them?
stochastic-processes markov-chains
Let $X_n:n=0,1,2,ldots$ be a Markov chain with transition probabilities as given below:

Determine the period of each state.
The answer is "The only state with period $> 1$ is $1$, which has period $3$. I don't understand why other states like $2$, $3$, $5$, $6$ are not with period $3$, they can also take $3$ steps back to themselves, can't them?
stochastic-processes markov-chains
edited Dec 13 '15 at 12:11
Math1000
18.5k31644
18.5k31644
asked Dec 13 '15 at 11:08
whoisit
386111
386111
2
You're right. All states except state $4$ takes $3n$ steps back to itself.
â GNU Supporter
Dec 13 '15 at 12:17
add a comment |Â
2
You're right. All states except state $4$ takes $3n$ steps back to itself.
â GNU Supporter
Dec 13 '15 at 12:17
2
2
You're right. All states except state $4$ takes $3n$ steps back to itself.
â GNU Supporter
Dec 13 '15 at 12:17
You're right. All states except state $4$ takes $3n$ steps back to itself.
â GNU Supporter
Dec 13 '15 at 12:17
add a comment |Â
1 Answer
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The period of a state $i$ is
$$d(i) = mathrmlcdn : P_ii^n > 0 . $$
If two states $i$ and $j$ communicate, that is, there exist $m,n>0$ such that $P_ij^n>0$ and $P_ji^m>0$, then $d(i)=d(j)$. By inspection, states $1, 2, 3, 5, 6$ all communicate. So you are correct.
1
Should lcd be gcd?
â Mick A
Dec 13 '15 at 12:39
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
0
down vote
The period of a state $i$ is
$$d(i) = mathrmlcdn : P_ii^n > 0 . $$
If two states $i$ and $j$ communicate, that is, there exist $m,n>0$ such that $P_ij^n>0$ and $P_ji^m>0$, then $d(i)=d(j)$. By inspection, states $1, 2, 3, 5, 6$ all communicate. So you are correct.
1
Should lcd be gcd?
â Mick A
Dec 13 '15 at 12:39
add a comment |Â
up vote
0
down vote
The period of a state $i$ is
$$d(i) = mathrmlcdn : P_ii^n > 0 . $$
If two states $i$ and $j$ communicate, that is, there exist $m,n>0$ such that $P_ij^n>0$ and $P_ji^m>0$, then $d(i)=d(j)$. By inspection, states $1, 2, 3, 5, 6$ all communicate. So you are correct.
1
Should lcd be gcd?
â Mick A
Dec 13 '15 at 12:39
add a comment |Â
up vote
0
down vote
up vote
0
down vote
The period of a state $i$ is
$$d(i) = mathrmlcdn : P_ii^n > 0 . $$
If two states $i$ and $j$ communicate, that is, there exist $m,n>0$ such that $P_ij^n>0$ and $P_ji^m>0$, then $d(i)=d(j)$. By inspection, states $1, 2, 3, 5, 6$ all communicate. So you are correct.
The period of a state $i$ is
$$d(i) = mathrmlcdn : P_ii^n > 0 . $$
If two states $i$ and $j$ communicate, that is, there exist $m,n>0$ such that $P_ij^n>0$ and $P_ji^m>0$, then $d(i)=d(j)$. By inspection, states $1, 2, 3, 5, 6$ all communicate. So you are correct.
answered Dec 13 '15 at 12:28
Math1000
18.5k31644
18.5k31644
1
Should lcd be gcd?
â Mick A
Dec 13 '15 at 12:39
add a comment |Â
1
Should lcd be gcd?
â Mick A
Dec 13 '15 at 12:39
1
1
Should lcd be gcd?
â Mick A
Dec 13 '15 at 12:39
Should lcd be gcd?
â Mick A
Dec 13 '15 at 12:39
add a comment |Â
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2
You're right. All states except state $4$ takes $3n$ steps back to itself.
â GNU Supporter
Dec 13 '15 at 12:17