$mathbb Z^n/langle (a,…,a) rangle cong mathbb Z^{n-1} oplus mathbb Z/langle a rangle$












8












$begingroup$


I am trying to show the isomorphism



$$mathbb Z^n/langle (a,...,a) rangle cong mathbb Z^{n-1} oplus mathbb Z/langle a rangle.$$



I've tried to define $psi:mathbb Z^n to mathbb Z^{n-1} oplus mathbb Z/langle a rangle$ an epimorphism with $ker(psi)=langle (a,...,a) rangle$ so to apply the first isomorphism theorem, but I couldn't come up with an appropiate morphism. Any hints or suggestions would be greatly appreciated.










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$endgroup$

















    8












    $begingroup$


    I am trying to show the isomorphism



    $$mathbb Z^n/langle (a,...,a) rangle cong mathbb Z^{n-1} oplus mathbb Z/langle a rangle.$$



    I've tried to define $psi:mathbb Z^n to mathbb Z^{n-1} oplus mathbb Z/langle a rangle$ an epimorphism with $ker(psi)=langle (a,...,a) rangle$ so to apply the first isomorphism theorem, but I couldn't come up with an appropiate morphism. Any hints or suggestions would be greatly appreciated.










    share|cite|improve this question











    $endgroup$















      8












      8








      8


      2



      $begingroup$


      I am trying to show the isomorphism



      $$mathbb Z^n/langle (a,...,a) rangle cong mathbb Z^{n-1} oplus mathbb Z/langle a rangle.$$



      I've tried to define $psi:mathbb Z^n to mathbb Z^{n-1} oplus mathbb Z/langle a rangle$ an epimorphism with $ker(psi)=langle (a,...,a) rangle$ so to apply the first isomorphism theorem, but I couldn't come up with an appropiate morphism. Any hints or suggestions would be greatly appreciated.










      share|cite|improve this question











      $endgroup$




      I am trying to show the isomorphism



      $$mathbb Z^n/langle (a,...,a) rangle cong mathbb Z^{n-1} oplus mathbb Z/langle a rangle.$$



      I've tried to define $psi:mathbb Z^n to mathbb Z^{n-1} oplus mathbb Z/langle a rangle$ an epimorphism with $ker(psi)=langle (a,...,a) rangle$ so to apply the first isomorphism theorem, but I couldn't come up with an appropiate morphism. Any hints or suggestions would be greatly appreciated.







      abstract-algebra group-theory






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      share|cite|improve this question













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      share|cite|improve this question








      edited Dec 1 '14 at 20:38









      user26857

      39.4k124183




      39.4k124183










      asked Dec 1 '14 at 20:15









      user156441user156441

      1,4461525




      1,4461525






















          3 Answers
          3






          active

          oldest

          votes


















          9












          $begingroup$

          If you want to use the first isomorphism theorem, then define $psi:mathbb Z^n to mathbb Z^{n-1} oplus mathbb Z/langle a rangle$ by $psi(x_1,dots,x_n)=(x_2-x_1,dots,x_n-x_1,bar x_1)$. Check that $psi$ is a surjective homomorphism and $kerpsi=langle (a,dots,a) rangle$.






          share|cite|improve this answer









          $endgroup$





















            9












            $begingroup$

            The following: $$(1,0,dots,0), (0,1,0,dots,0), dots, (0,dots,0,1,0), (1,1,dots, 1)$$ is a basis of $mathbb{Z}^n$ and $(a,dots,a)$ corresponds to $(0,dots,0,a)$ in this new basis. Your group is thus the isomorphic to the quotient:
            $$mathbb{Z}^n / langle (0, dots, 0, a) rangle cong mathbb{Z}^{n-1} oplus mathbb{Z}/(a).$$






            share|cite|improve this answer











            $endgroup$













            • $begingroup$
              @lhf : well, this is what I did 2 years ago: math.stackexchange.com/questions/1910883
              $endgroup$
              – Alphonse
              Dec 21 '18 at 16:33



















            5












            $begingroup$

            $mathbb{Z}^n/langle (a,dotsc,a)$ is an abelian group with the presentation $langle e_1,dotsc,e_n : a e_1 + cdots + a e_n = 0}$. Observe that $e_1,dotsc,e_{n-1},e_1+cdots+e_n$ is also a generating system and $a(e_1+cdots+e_n)=0$. Hence, we obtain a homomorphism from $langle f_1,dotsc,f_n : a f_n = 0 rangle$. One then constructs its inverse.






            share|cite|improve this answer











            $endgroup$













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              3 Answers
              3






              active

              oldest

              votes








              3 Answers
              3






              active

              oldest

              votes









              active

              oldest

              votes






              active

              oldest

              votes









              9












              $begingroup$

              If you want to use the first isomorphism theorem, then define $psi:mathbb Z^n to mathbb Z^{n-1} oplus mathbb Z/langle a rangle$ by $psi(x_1,dots,x_n)=(x_2-x_1,dots,x_n-x_1,bar x_1)$. Check that $psi$ is a surjective homomorphism and $kerpsi=langle (a,dots,a) rangle$.






              share|cite|improve this answer









              $endgroup$


















                9












                $begingroup$

                If you want to use the first isomorphism theorem, then define $psi:mathbb Z^n to mathbb Z^{n-1} oplus mathbb Z/langle a rangle$ by $psi(x_1,dots,x_n)=(x_2-x_1,dots,x_n-x_1,bar x_1)$. Check that $psi$ is a surjective homomorphism and $kerpsi=langle (a,dots,a) rangle$.






                share|cite|improve this answer









                $endgroup$
















                  9












                  9








                  9





                  $begingroup$

                  If you want to use the first isomorphism theorem, then define $psi:mathbb Z^n to mathbb Z^{n-1} oplus mathbb Z/langle a rangle$ by $psi(x_1,dots,x_n)=(x_2-x_1,dots,x_n-x_1,bar x_1)$. Check that $psi$ is a surjective homomorphism and $kerpsi=langle (a,dots,a) rangle$.






                  share|cite|improve this answer









                  $endgroup$



                  If you want to use the first isomorphism theorem, then define $psi:mathbb Z^n to mathbb Z^{n-1} oplus mathbb Z/langle a rangle$ by $psi(x_1,dots,x_n)=(x_2-x_1,dots,x_n-x_1,bar x_1)$. Check that $psi$ is a surjective homomorphism and $kerpsi=langle (a,dots,a) rangle$.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Dec 1 '14 at 20:30









                  user26857user26857

                  39.4k124183




                  39.4k124183























                      9












                      $begingroup$

                      The following: $$(1,0,dots,0), (0,1,0,dots,0), dots, (0,dots,0,1,0), (1,1,dots, 1)$$ is a basis of $mathbb{Z}^n$ and $(a,dots,a)$ corresponds to $(0,dots,0,a)$ in this new basis. Your group is thus the isomorphic to the quotient:
                      $$mathbb{Z}^n / langle (0, dots, 0, a) rangle cong mathbb{Z}^{n-1} oplus mathbb{Z}/(a).$$






                      share|cite|improve this answer











                      $endgroup$













                      • $begingroup$
                        @lhf : well, this is what I did 2 years ago: math.stackexchange.com/questions/1910883
                        $endgroup$
                        – Alphonse
                        Dec 21 '18 at 16:33
















                      9












                      $begingroup$

                      The following: $$(1,0,dots,0), (0,1,0,dots,0), dots, (0,dots,0,1,0), (1,1,dots, 1)$$ is a basis of $mathbb{Z}^n$ and $(a,dots,a)$ corresponds to $(0,dots,0,a)$ in this new basis. Your group is thus the isomorphic to the quotient:
                      $$mathbb{Z}^n / langle (0, dots, 0, a) rangle cong mathbb{Z}^{n-1} oplus mathbb{Z}/(a).$$






                      share|cite|improve this answer











                      $endgroup$













                      • $begingroup$
                        @lhf : well, this is what I did 2 years ago: math.stackexchange.com/questions/1910883
                        $endgroup$
                        – Alphonse
                        Dec 21 '18 at 16:33














                      9












                      9








                      9





                      $begingroup$

                      The following: $$(1,0,dots,0), (0,1,0,dots,0), dots, (0,dots,0,1,0), (1,1,dots, 1)$$ is a basis of $mathbb{Z}^n$ and $(a,dots,a)$ corresponds to $(0,dots,0,a)$ in this new basis. Your group is thus the isomorphic to the quotient:
                      $$mathbb{Z}^n / langle (0, dots, 0, a) rangle cong mathbb{Z}^{n-1} oplus mathbb{Z}/(a).$$






                      share|cite|improve this answer











                      $endgroup$



                      The following: $$(1,0,dots,0), (0,1,0,dots,0), dots, (0,dots,0,1,0), (1,1,dots, 1)$$ is a basis of $mathbb{Z}^n$ and $(a,dots,a)$ corresponds to $(0,dots,0,a)$ in this new basis. Your group is thus the isomorphic to the quotient:
                      $$mathbb{Z}^n / langle (0, dots, 0, a) rangle cong mathbb{Z}^{n-1} oplus mathbb{Z}/(a).$$







                      share|cite|improve this answer














                      share|cite|improve this answer



                      share|cite|improve this answer








                      edited Jan 2 '15 at 11:16

























                      answered Dec 1 '14 at 20:19









                      Najib IdrissiNajib Idrissi

                      41.1k471139




                      41.1k471139












                      • $begingroup$
                        @lhf : well, this is what I did 2 years ago: math.stackexchange.com/questions/1910883
                        $endgroup$
                        – Alphonse
                        Dec 21 '18 at 16:33


















                      • $begingroup$
                        @lhf : well, this is what I did 2 years ago: math.stackexchange.com/questions/1910883
                        $endgroup$
                        – Alphonse
                        Dec 21 '18 at 16:33
















                      $begingroup$
                      @lhf : well, this is what I did 2 years ago: math.stackexchange.com/questions/1910883
                      $endgroup$
                      – Alphonse
                      Dec 21 '18 at 16:33




                      $begingroup$
                      @lhf : well, this is what I did 2 years ago: math.stackexchange.com/questions/1910883
                      $endgroup$
                      – Alphonse
                      Dec 21 '18 at 16:33











                      5












                      $begingroup$

                      $mathbb{Z}^n/langle (a,dotsc,a)$ is an abelian group with the presentation $langle e_1,dotsc,e_n : a e_1 + cdots + a e_n = 0}$. Observe that $e_1,dotsc,e_{n-1},e_1+cdots+e_n$ is also a generating system and $a(e_1+cdots+e_n)=0$. Hence, we obtain a homomorphism from $langle f_1,dotsc,f_n : a f_n = 0 rangle$. One then constructs its inverse.






                      share|cite|improve this answer











                      $endgroup$


















                        5












                        $begingroup$

                        $mathbb{Z}^n/langle (a,dotsc,a)$ is an abelian group with the presentation $langle e_1,dotsc,e_n : a e_1 + cdots + a e_n = 0}$. Observe that $e_1,dotsc,e_{n-1},e_1+cdots+e_n$ is also a generating system and $a(e_1+cdots+e_n)=0$. Hence, we obtain a homomorphism from $langle f_1,dotsc,f_n : a f_n = 0 rangle$. One then constructs its inverse.






                        share|cite|improve this answer











                        $endgroup$
















                          5












                          5








                          5





                          $begingroup$

                          $mathbb{Z}^n/langle (a,dotsc,a)$ is an abelian group with the presentation $langle e_1,dotsc,e_n : a e_1 + cdots + a e_n = 0}$. Observe that $e_1,dotsc,e_{n-1},e_1+cdots+e_n$ is also a generating system and $a(e_1+cdots+e_n)=0$. Hence, we obtain a homomorphism from $langle f_1,dotsc,f_n : a f_n = 0 rangle$. One then constructs its inverse.






                          share|cite|improve this answer











                          $endgroup$



                          $mathbb{Z}^n/langle (a,dotsc,a)$ is an abelian group with the presentation $langle e_1,dotsc,e_n : a e_1 + cdots + a e_n = 0}$. Observe that $e_1,dotsc,e_{n-1},e_1+cdots+e_n$ is also a generating system and $a(e_1+cdots+e_n)=0$. Hence, we obtain a homomorphism from $langle f_1,dotsc,f_n : a f_n = 0 rangle$. One then constructs its inverse.







                          share|cite|improve this answer














                          share|cite|improve this answer



                          share|cite|improve this answer








                          edited Dec 21 '18 at 9:51









                          user26857

                          39.4k124183




                          39.4k124183










                          answered Dec 1 '14 at 20:20









                          Martin BrandenburgMartin Brandenburg

                          108k13158328




                          108k13158328






























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