If $f(g(g(f(x)))) = x$ then does $f(g(x)) = g(f(x))$? [closed]












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Let $S$ be a set and $f, g: S to S$ such that for all $x in S$, $f(g(g(f(x)))) = x$. Is it true that for all $x in S$, $f(g(x)) = g(f(x))$?










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closed as off-topic by Saad, Nosrati, RRL, Brahadeesh, user10354138 Dec 17 '18 at 5:24


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Saad, Nosrati, RRL, Brahadeesh, user10354138

If this question can be reworded to fit the rules in the help center, please edit the question.





















    0












    $begingroup$


    Let $S$ be a set and $f, g: S to S$ such that for all $x in S$, $f(g(g(f(x)))) = x$. Is it true that for all $x in S$, $f(g(x)) = g(f(x))$?










    share|cite|improve this question









    $endgroup$



    closed as off-topic by Saad, Nosrati, RRL, Brahadeesh, user10354138 Dec 17 '18 at 5:24


    This question appears to be off-topic. The users who voted to close gave this specific reason:


    • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Saad, Nosrati, RRL, Brahadeesh, user10354138

    If this question can be reworded to fit the rules in the help center, please edit the question.



















      0












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      0





      $begingroup$


      Let $S$ be a set and $f, g: S to S$ such that for all $x in S$, $f(g(g(f(x)))) = x$. Is it true that for all $x in S$, $f(g(x)) = g(f(x))$?










      share|cite|improve this question









      $endgroup$




      Let $S$ be a set and $f, g: S to S$ such that for all $x in S$, $f(g(g(f(x)))) = x$. Is it true that for all $x in S$, $f(g(x)) = g(f(x))$?







      real-analysis






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      asked Dec 17 '18 at 1:57









      user627084user627084

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      31




      closed as off-topic by Saad, Nosrati, RRL, Brahadeesh, user10354138 Dec 17 '18 at 5:24


      This question appears to be off-topic. The users who voted to close gave this specific reason:


      • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Saad, Nosrati, RRL, Brahadeesh, user10354138

      If this question can be reworded to fit the rules in the help center, please edit the question.







      closed as off-topic by Saad, Nosrati, RRL, Brahadeesh, user10354138 Dec 17 '18 at 5:24


      This question appears to be off-topic. The users who voted to close gave this specific reason:


      • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Saad, Nosrati, RRL, Brahadeesh, user10354138

      If this question can be reworded to fit the rules in the help center, please edit the question.






















          1 Answer
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          3












          $begingroup$

          Try $g(x) = -x$ and $f(x) = x/(x-1)$ (on a suitable $S$ where you won't end up dividing by $0$, e.g. the irrationals).






          share|cite|improve this answer









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            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            3












            $begingroup$

            Try $g(x) = -x$ and $f(x) = x/(x-1)$ (on a suitable $S$ where you won't end up dividing by $0$, e.g. the irrationals).






            share|cite|improve this answer









            $endgroup$


















              3












              $begingroup$

              Try $g(x) = -x$ and $f(x) = x/(x-1)$ (on a suitable $S$ where you won't end up dividing by $0$, e.g. the irrationals).






              share|cite|improve this answer









              $endgroup$
















                3












                3








                3





                $begingroup$

                Try $g(x) = -x$ and $f(x) = x/(x-1)$ (on a suitable $S$ where you won't end up dividing by $0$, e.g. the irrationals).






                share|cite|improve this answer









                $endgroup$



                Try $g(x) = -x$ and $f(x) = x/(x-1)$ (on a suitable $S$ where you won't end up dividing by $0$, e.g. the irrationals).







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Dec 17 '18 at 2:05









                Robert IsraelRobert Israel

                327k23216470




                327k23216470















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