Compute all $X_{g}$ and all $G_{x}$ for $X = left {1, 2, 3right }$, $G = S_{3} = left {(1), (12), (13), (23),...











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Compute all $X_{g}$ and all $G_{x}$ for $X = left {1, 2, 3right }$, $G = S_{3} = left {(1), (12), (13), (23), (123), (132)right }$.




Can someone give me a head start to this problem?



$X_{g}=left {xin X: gx=xright }$. So how do I find $X_{(12)}$? Do I calculate $(12)(1),(12)(2),(12)(3)$?










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  • 1




    Yes. But then, you see, $(12)$ is the permutation that affects only $1$ and $2$, so it doesn't affect any other number. So $X_{(12)}$ should be immediate.
    – Scientifica
    Dec 5 at 19:01










  • And so $X_{(12)}=left {3right }$?
    – numericalorange
    Dec 5 at 19:17








  • 1




    That's absolutely right!
    – Scientifica
    Dec 5 at 19:30










  • @Scientifica Oh, wow, I feel so happy that you helped me understand this so easily!!
    – numericalorange
    Dec 5 at 19:31






  • 1




    I'm gonna post this as an answer so that your question is answered.
    – Scientifica
    Dec 5 at 19:32















up vote
1
down vote

favorite
1













Compute all $X_{g}$ and all $G_{x}$ for $X = left {1, 2, 3right }$, $G = S_{3} = left {(1), (12), (13), (23), (123), (132)right }$.




Can someone give me a head start to this problem?



$X_{g}=left {xin X: gx=xright }$. So how do I find $X_{(12)}$? Do I calculate $(12)(1),(12)(2),(12)(3)$?










share|cite|improve this question




















  • 1




    Yes. But then, you see, $(12)$ is the permutation that affects only $1$ and $2$, so it doesn't affect any other number. So $X_{(12)}$ should be immediate.
    – Scientifica
    Dec 5 at 19:01










  • And so $X_{(12)}=left {3right }$?
    – numericalorange
    Dec 5 at 19:17








  • 1




    That's absolutely right!
    – Scientifica
    Dec 5 at 19:30










  • @Scientifica Oh, wow, I feel so happy that you helped me understand this so easily!!
    – numericalorange
    Dec 5 at 19:31






  • 1




    I'm gonna post this as an answer so that your question is answered.
    – Scientifica
    Dec 5 at 19:32













up vote
1
down vote

favorite
1









up vote
1
down vote

favorite
1






1






Compute all $X_{g}$ and all $G_{x}$ for $X = left {1, 2, 3right }$, $G = S_{3} = left {(1), (12), (13), (23), (123), (132)right }$.




Can someone give me a head start to this problem?



$X_{g}=left {xin X: gx=xright }$. So how do I find $X_{(12)}$? Do I calculate $(12)(1),(12)(2),(12)(3)$?










share|cite|improve this question
















Compute all $X_{g}$ and all $G_{x}$ for $X = left {1, 2, 3right }$, $G = S_{3} = left {(1), (12), (13), (23), (123), (132)right }$.




Can someone give me a head start to this problem?



$X_{g}=left {xin X: gx=xright }$. So how do I find $X_{(12)}$? Do I calculate $(12)(1),(12)(2),(12)(3)$?







abstract-algebra group-theory permutations group-actions permutation-cycles






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edited Dec 5 at 19:34









Scientifica

6,34141333




6,34141333










asked Dec 5 at 18:56









numericalorange

1,719311




1,719311








  • 1




    Yes. But then, you see, $(12)$ is the permutation that affects only $1$ and $2$, so it doesn't affect any other number. So $X_{(12)}$ should be immediate.
    – Scientifica
    Dec 5 at 19:01










  • And so $X_{(12)}=left {3right }$?
    – numericalorange
    Dec 5 at 19:17








  • 1




    That's absolutely right!
    – Scientifica
    Dec 5 at 19:30










  • @Scientifica Oh, wow, I feel so happy that you helped me understand this so easily!!
    – numericalorange
    Dec 5 at 19:31






  • 1




    I'm gonna post this as an answer so that your question is answered.
    – Scientifica
    Dec 5 at 19:32














  • 1




    Yes. But then, you see, $(12)$ is the permutation that affects only $1$ and $2$, so it doesn't affect any other number. So $X_{(12)}$ should be immediate.
    – Scientifica
    Dec 5 at 19:01










  • And so $X_{(12)}=left {3right }$?
    – numericalorange
    Dec 5 at 19:17








  • 1




    That's absolutely right!
    – Scientifica
    Dec 5 at 19:30










  • @Scientifica Oh, wow, I feel so happy that you helped me understand this so easily!!
    – numericalorange
    Dec 5 at 19:31






  • 1




    I'm gonna post this as an answer so that your question is answered.
    – Scientifica
    Dec 5 at 19:32








1




1




Yes. But then, you see, $(12)$ is the permutation that affects only $1$ and $2$, so it doesn't affect any other number. So $X_{(12)}$ should be immediate.
– Scientifica
Dec 5 at 19:01




Yes. But then, you see, $(12)$ is the permutation that affects only $1$ and $2$, so it doesn't affect any other number. So $X_{(12)}$ should be immediate.
– Scientifica
Dec 5 at 19:01












And so $X_{(12)}=left {3right }$?
– numericalorange
Dec 5 at 19:17






And so $X_{(12)}=left {3right }$?
– numericalorange
Dec 5 at 19:17






1




1




That's absolutely right!
– Scientifica
Dec 5 at 19:30




That's absolutely right!
– Scientifica
Dec 5 at 19:30












@Scientifica Oh, wow, I feel so happy that you helped me understand this so easily!!
– numericalorange
Dec 5 at 19:31




@Scientifica Oh, wow, I feel so happy that you helped me understand this so easily!!
– numericalorange
Dec 5 at 19:31




1




1




I'm gonna post this as an answer so that your question is answered.
– Scientifica
Dec 5 at 19:32




I'm gonna post this as an answer so that your question is answered.
– Scientifica
Dec 5 at 19:32










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Yes that's how you do it.



You can also easily see it as follows: the permutation $(12)$ affects $1$ and $2$, but no other element. So $X_{(12)}$ is immediate. The same remark allows you to quickly determine the $G_x$.






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    1 Answer
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    active

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    1 Answer
    1






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    active

    oldest

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    active

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    up vote
    1
    down vote



    accepted










    Yes that's how you do it.



    You can also easily see it as follows: the permutation $(12)$ affects $1$ and $2$, but no other element. So $X_{(12)}$ is immediate. The same remark allows you to quickly determine the $G_x$.






    share|cite|improve this answer

























      up vote
      1
      down vote



      accepted










      Yes that's how you do it.



      You can also easily see it as follows: the permutation $(12)$ affects $1$ and $2$, but no other element. So $X_{(12)}$ is immediate. The same remark allows you to quickly determine the $G_x$.






      share|cite|improve this answer























        up vote
        1
        down vote



        accepted







        up vote
        1
        down vote



        accepted






        Yes that's how you do it.



        You can also easily see it as follows: the permutation $(12)$ affects $1$ and $2$, but no other element. So $X_{(12)}$ is immediate. The same remark allows you to quickly determine the $G_x$.






        share|cite|improve this answer












        Yes that's how you do it.



        You can also easily see it as follows: the permutation $(12)$ affects $1$ and $2$, but no other element. So $X_{(12)}$ is immediate. The same remark allows you to quickly determine the $G_x$.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 5 at 19:34









        Scientifica

        6,34141333




        6,34141333






























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