What does order of element mean in the Symmetric Group?

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I have seen several references to "order" of an element in the Symmetric Group. Specifically, that the order of a cycle is the least common multiple of the lengths of the cycles in its decomposition.



But the Symmetric Group is not cyclic, and I'm only familiar with the concept of "order" for cyclic groups. So what does it mean in this context?










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    I have seen several references to "order" of an element in the Symmetric Group. Specifically, that the order of a cycle is the least common multiple of the lengths of the cycles in its decomposition.



    But the Symmetric Group is not cyclic, and I'm only familiar with the concept of "order" for cyclic groups. So what does it mean in this context?










    share|cite|improve this question







    New contributor




    Clotex is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      up vote
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      up vote
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      down vote

      favorite











      I have seen several references to "order" of an element in the Symmetric Group. Specifically, that the order of a cycle is the least common multiple of the lengths of the cycles in its decomposition.



      But the Symmetric Group is not cyclic, and I'm only familiar with the concept of "order" for cyclic groups. So what does it mean in this context?










      share|cite|improve this question







      New contributor




      Clotex is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      I have seen several references to "order" of an element in the Symmetric Group. Specifically, that the order of a cycle is the least common multiple of the lengths of the cycles in its decomposition.



      But the Symmetric Group is not cyclic, and I'm only familiar with the concept of "order" for cyclic groups. So what does it mean in this context?







      abstract-algebra group-theory symmetric-groups






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          The order of an element $g$ in a finite group $G$ is the smallest integer $n$ such that $g^n = e$ (the neutral element of the group). This is well-defined for every finite group $G$, so in particular for the Symmetric group as well.



          The Lagrange theorem implies indeed, that for any finite group $G$ with $p$ elements and any $g in G$, then $g^p = e$, which shows that every $g$ has finite order, smaller than $p$.






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            Since you know about cyclic groups.



            Think of order of an element in the symmetric group $S_n$ as the size of the cyclic group generated by it.



            Example 1: Let us take $S_3$. Take $g=(123)$. Consider the cyclic group generated by $g$, that is $<g>$. $<g>=(123),(132),(1)$. So order of $g$ is 3 since cardinality of $<g>$ is 3.



            Example 2: Consider $S_4$ and take $g=(12)(34)$ Then $<g>=(12)(34),(1)$. Since cardinality of $<g>$ is 2, order of $g$ is $2$.



            Example 3(Take it as an exercise): Consider $S_5$ and take $g=(123)(45)$. Find $<g>$ by explicitly writing each element and then calculate the order from $g$ from there






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              The order of an element $g$ in a finite group $G$ is the smallest integer $n$ such that $g^n = e$ (the neutral element of the group). This is well-defined for every finite group $G$, so in particular for the Symmetric group as well.



              The Lagrange theorem implies indeed, that for any finite group $G$ with $p$ elements and any $g in G$, then $g^p = e$, which shows that every $g$ has finite order, smaller than $p$.






              share|cite|improve this answer








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                up vote
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                The order of an element $g$ in a finite group $G$ is the smallest integer $n$ such that $g^n = e$ (the neutral element of the group). This is well-defined for every finite group $G$, so in particular for the Symmetric group as well.



                The Lagrange theorem implies indeed, that for any finite group $G$ with $p$ elements and any $g in G$, then $g^p = e$, which shows that every $g$ has finite order, smaller than $p$.






                share|cite|improve this answer








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                  up vote
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                  up vote
                  4
                  down vote









                  The order of an element $g$ in a finite group $G$ is the smallest integer $n$ such that $g^n = e$ (the neutral element of the group). This is well-defined for every finite group $G$, so in particular for the Symmetric group as well.



                  The Lagrange theorem implies indeed, that for any finite group $G$ with $p$ elements and any $g in G$, then $g^p = e$, which shows that every $g$ has finite order, smaller than $p$.






                  share|cite|improve this answer








                  New contributor




                  seamp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                  Check out our Code of Conduct.









                  The order of an element $g$ in a finite group $G$ is the smallest integer $n$ such that $g^n = e$ (the neutral element of the group). This is well-defined for every finite group $G$, so in particular for the Symmetric group as well.



                  The Lagrange theorem implies indeed, that for any finite group $G$ with $p$ elements and any $g in G$, then $g^p = e$, which shows that every $g$ has finite order, smaller than $p$.







                  share|cite|improve this answer








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                      up vote
                      3
                      down vote













                      Since you know about cyclic groups.



                      Think of order of an element in the symmetric group $S_n$ as the size of the cyclic group generated by it.



                      Example 1: Let us take $S_3$. Take $g=(123)$. Consider the cyclic group generated by $g$, that is $<g>$. $<g>=(123),(132),(1)$. So order of $g$ is 3 since cardinality of $<g>$ is 3.



                      Example 2: Consider $S_4$ and take $g=(12)(34)$ Then $<g>=(12)(34),(1)$. Since cardinality of $<g>$ is 2, order of $g$ is $2$.



                      Example 3(Take it as an exercise): Consider $S_5$ and take $g=(123)(45)$. Find $<g>$ by explicitly writing each element and then calculate the order from $g$ from there






                      share|cite|improve this answer


























                        up vote
                        3
                        down vote













                        Since you know about cyclic groups.



                        Think of order of an element in the symmetric group $S_n$ as the size of the cyclic group generated by it.



                        Example 1: Let us take $S_3$. Take $g=(123)$. Consider the cyclic group generated by $g$, that is $<g>$. $<g>=(123),(132),(1)$. So order of $g$ is 3 since cardinality of $<g>$ is 3.



                        Example 2: Consider $S_4$ and take $g=(12)(34)$ Then $<g>=(12)(34),(1)$. Since cardinality of $<g>$ is 2, order of $g$ is $2$.



                        Example 3(Take it as an exercise): Consider $S_5$ and take $g=(123)(45)$. Find $<g>$ by explicitly writing each element and then calculate the order from $g$ from there






                        share|cite|improve this answer
























                          up vote
                          3
                          down vote










                          up vote
                          3
                          down vote









                          Since you know about cyclic groups.



                          Think of order of an element in the symmetric group $S_n$ as the size of the cyclic group generated by it.



                          Example 1: Let us take $S_3$. Take $g=(123)$. Consider the cyclic group generated by $g$, that is $<g>$. $<g>=(123),(132),(1)$. So order of $g$ is 3 since cardinality of $<g>$ is 3.



                          Example 2: Consider $S_4$ and take $g=(12)(34)$ Then $<g>=(12)(34),(1)$. Since cardinality of $<g>$ is 2, order of $g$ is $2$.



                          Example 3(Take it as an exercise): Consider $S_5$ and take $g=(123)(45)$. Find $<g>$ by explicitly writing each element and then calculate the order from $g$ from there






                          share|cite|improve this answer














                          Since you know about cyclic groups.



                          Think of order of an element in the symmetric group $S_n$ as the size of the cyclic group generated by it.



                          Example 1: Let us take $S_3$. Take $g=(123)$. Consider the cyclic group generated by $g$, that is $<g>$. $<g>=(123),(132),(1)$. So order of $g$ is 3 since cardinality of $<g>$ is 3.



                          Example 2: Consider $S_4$ and take $g=(12)(34)$ Then $<g>=(12)(34),(1)$. Since cardinality of $<g>$ is 2, order of $g$ is $2$.



                          Example 3(Take it as an exercise): Consider $S_5$ and take $g=(123)(45)$. Find $<g>$ by explicitly writing each element and then calculate the order from $g$ from there







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