Homomorphism: How do we get the equality?

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Let $Z = (mathbbZ,+)$ the additive group of integers and $G = (M,star )$ an arbitrary group.



I want to show that for all $a in G$ the map $phi_a : Z rightarrow G$ defined by $phi_a(k) = a^k$ is an homomorphism from $Z$ to $G$.



Let $m,nin Z$. Then we have that $phi_a(m+n)=a^m+n$ and $phi_a(m)star phi_a(n)=a^mstar a^n$.



Do we consider $star$ as a multiplication and so $a^m+n=a^mstar a^n$, or how do we get the equality?







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    up vote
    1
    down vote

    favorite












    Let $Z = (mathbbZ,+)$ the additive group of integers and $G = (M,star )$ an arbitrary group.



    I want to show that for all $a in G$ the map $phi_a : Z rightarrow G$ defined by $phi_a(k) = a^k$ is an homomorphism from $Z$ to $G$.



    Let $m,nin Z$. Then we have that $phi_a(m+n)=a^m+n$ and $phi_a(m)star phi_a(n)=a^mstar a^n$.



    Do we consider $star$ as a multiplication and so $a^m+n=a^mstar a^n$, or how do we get the equality?







    share|cite|improve this question






















      up vote
      1
      down vote

      favorite









      up vote
      1
      down vote

      favorite











      Let $Z = (mathbbZ,+)$ the additive group of integers and $G = (M,star )$ an arbitrary group.



      I want to show that for all $a in G$ the map $phi_a : Z rightarrow G$ defined by $phi_a(k) = a^k$ is an homomorphism from $Z$ to $G$.



      Let $m,nin Z$. Then we have that $phi_a(m+n)=a^m+n$ and $phi_a(m)star phi_a(n)=a^mstar a^n$.



      Do we consider $star$ as a multiplication and so $a^m+n=a^mstar a^n$, or how do we get the equality?







      share|cite|improve this question












      Let $Z = (mathbbZ,+)$ the additive group of integers and $G = (M,star )$ an arbitrary group.



      I want to show that for all $a in G$ the map $phi_a : Z rightarrow G$ defined by $phi_a(k) = a^k$ is an homomorphism from $Z$ to $G$.



      Let $m,nin Z$. Then we have that $phi_a(m+n)=a^m+n$ and $phi_a(m)star phi_a(n)=a^mstar a^n$.



      Do we consider $star$ as a multiplication and so $a^m+n=a^mstar a^n$, or how do we get the equality?









      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Aug 26 at 22:56









      Mary Star

      2,82982056




      2,82982056




















          2 Answers
          2






          active

          oldest

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          up vote
          2
          down vote



          accepted










          The question as phrased is leaving it to you to figure out that the notation $a^n$ means $overbracea star ldots star a^mbox$n$ $a$s$ . I.e. $a^n$ is defined by:



          $$
          beginalign
          a^0 &= e \
          a^n+1 &= a^n star a
          endalign
          $$



          where $e$ is the identity element of the group $G$. Now you can prove by induction that $a^m star a^n = a^m+n$.






          share|cite|improve this answer




















          • Thank you!! :-)
            – Mary Star
            2 days ago

















          up vote
          1
          down vote













          Yes we see that as the multiplication between elements of group.



          Since $a^m$ and $ a^n$ are elements of your group, $a^m star a^n = a^m+n$ is given as the associative property of the group operation.






          share|cite|improve this answer




















          • Thank you!! :-)
            – Mary Star
            2 days ago










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          2 Answers
          2






          active

          oldest

          votes








          2 Answers
          2






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes








          up vote
          2
          down vote



          accepted










          The question as phrased is leaving it to you to figure out that the notation $a^n$ means $overbracea star ldots star a^mbox$n$ $a$s$ . I.e. $a^n$ is defined by:



          $$
          beginalign
          a^0 &= e \
          a^n+1 &= a^n star a
          endalign
          $$



          where $e$ is the identity element of the group $G$. Now you can prove by induction that $a^m star a^n = a^m+n$.






          share|cite|improve this answer




















          • Thank you!! :-)
            – Mary Star
            2 days ago














          up vote
          2
          down vote



          accepted










          The question as phrased is leaving it to you to figure out that the notation $a^n$ means $overbracea star ldots star a^mbox$n$ $a$s$ . I.e. $a^n$ is defined by:



          $$
          beginalign
          a^0 &= e \
          a^n+1 &= a^n star a
          endalign
          $$



          where $e$ is the identity element of the group $G$. Now you can prove by induction that $a^m star a^n = a^m+n$.






          share|cite|improve this answer




















          • Thank you!! :-)
            – Mary Star
            2 days ago












          up vote
          2
          down vote



          accepted







          up vote
          2
          down vote



          accepted






          The question as phrased is leaving it to you to figure out that the notation $a^n$ means $overbracea star ldots star a^mbox$n$ $a$s$ . I.e. $a^n$ is defined by:



          $$
          beginalign
          a^0 &= e \
          a^n+1 &= a^n star a
          endalign
          $$



          where $e$ is the identity element of the group $G$. Now you can prove by induction that $a^m star a^n = a^m+n$.






          share|cite|improve this answer












          The question as phrased is leaving it to you to figure out that the notation $a^n$ means $overbracea star ldots star a^mbox$n$ $a$s$ . I.e. $a^n$ is defined by:



          $$
          beginalign
          a^0 &= e \
          a^n+1 &= a^n star a
          endalign
          $$



          where $e$ is the identity element of the group $G$. Now you can prove by induction that $a^m star a^n = a^m+n$.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Aug 26 at 23:29









          Rob Arthan

          27.4k42865




          27.4k42865











          • Thank you!! :-)
            – Mary Star
            2 days ago
















          • Thank you!! :-)
            – Mary Star
            2 days ago















          Thank you!! :-)
          – Mary Star
          2 days ago




          Thank you!! :-)
          – Mary Star
          2 days ago










          up vote
          1
          down vote













          Yes we see that as the multiplication between elements of group.



          Since $a^m$ and $ a^n$ are elements of your group, $a^m star a^n = a^m+n$ is given as the associative property of the group operation.






          share|cite|improve this answer




















          • Thank you!! :-)
            – Mary Star
            2 days ago














          up vote
          1
          down vote













          Yes we see that as the multiplication between elements of group.



          Since $a^m$ and $ a^n$ are elements of your group, $a^m star a^n = a^m+n$ is given as the associative property of the group operation.






          share|cite|improve this answer




















          • Thank you!! :-)
            – Mary Star
            2 days ago












          up vote
          1
          down vote










          up vote
          1
          down vote









          Yes we see that as the multiplication between elements of group.



          Since $a^m$ and $ a^n$ are elements of your group, $a^m star a^n = a^m+n$ is given as the associative property of the group operation.






          share|cite|improve this answer












          Yes we see that as the multiplication between elements of group.



          Since $a^m$ and $ a^n$ are elements of your group, $a^m star a^n = a^m+n$ is given as the associative property of the group operation.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Aug 26 at 23:08









          Mohammad Riazi-Kermani

          30.6k41852




          30.6k41852











          • Thank you!! :-)
            – Mary Star
            2 days ago
















          • Thank you!! :-)
            – Mary Star
            2 days ago















          Thank you!! :-)
          – Mary Star
          2 days ago




          Thank you!! :-)
          – Mary Star
          2 days ago

















           

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