Finitely generated Tensor Product












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Does $M otimes N $ finitely generated imply that $M$ and $N$ are also finitely generated? I know that the converse is true, but I'm not really sure about this one. Thanks.










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    1












    $begingroup$


    Does $M otimes N $ finitely generated imply that $M$ and $N$ are also finitely generated? I know that the converse is true, but I'm not really sure about this one. Thanks.










    share|cite|improve this question











    $endgroup$















      1












      1








      1





      $begingroup$


      Does $M otimes N $ finitely generated imply that $M$ and $N$ are also finitely generated? I know that the converse is true, but I'm not really sure about this one. Thanks.










      share|cite|improve this question











      $endgroup$




      Does $M otimes N $ finitely generated imply that $M$ and $N$ are also finitely generated? I know that the converse is true, but I'm not really sure about this one. Thanks.







      abstract-algebra modules






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      edited Jan 22 at 20:43









      user26857

      39.3k124183




      39.3k124183










      asked Jan 22 at 17:39









      Pedro SantosPedro Santos

      1539




      1539






















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          $begingroup$

          No : there are examples where neither is finitely generated, and examples where one of them is and not the other: take for instance $mathbb{Q}otimestext{(any torsion abelian group)}$, which is $0$.



          Now it's known that there are finitely generated and infinitely generated torsion abelian groups, so that's it.






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          • $begingroup$
            Oh yeah , Thanks.
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:44










          • $begingroup$
            Can u give me an example of a infinitely generated torsion abelian group? Does $mathbb{Z}_{2}^mathbb{N} work ?$
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:49












          • $begingroup$
            nevermind i understand it now
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:56











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          $begingroup$

          No : there are examples where neither is finitely generated, and examples where one of them is and not the other: take for instance $mathbb{Q}otimestext{(any torsion abelian group)}$, which is $0$.



          Now it's known that there are finitely generated and infinitely generated torsion abelian groups, so that's it.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Oh yeah , Thanks.
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:44










          • $begingroup$
            Can u give me an example of a infinitely generated torsion abelian group? Does $mathbb{Z}_{2}^mathbb{N} work ?$
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:49












          • $begingroup$
            nevermind i understand it now
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:56
















          2












          $begingroup$

          No : there are examples where neither is finitely generated, and examples where one of them is and not the other: take for instance $mathbb{Q}otimestext{(any torsion abelian group)}$, which is $0$.



          Now it's known that there are finitely generated and infinitely generated torsion abelian groups, so that's it.






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Oh yeah , Thanks.
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:44










          • $begingroup$
            Can u give me an example of a infinitely generated torsion abelian group? Does $mathbb{Z}_{2}^mathbb{N} work ?$
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:49












          • $begingroup$
            nevermind i understand it now
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:56














          2












          2








          2





          $begingroup$

          No : there are examples where neither is finitely generated, and examples where one of them is and not the other: take for instance $mathbb{Q}otimestext{(any torsion abelian group)}$, which is $0$.



          Now it's known that there are finitely generated and infinitely generated torsion abelian groups, so that's it.






          share|cite|improve this answer











          $endgroup$



          No : there are examples where neither is finitely generated, and examples where one of them is and not the other: take for instance $mathbb{Q}otimestext{(any torsion abelian group)}$, which is $0$.



          Now it's known that there are finitely generated and infinitely generated torsion abelian groups, so that's it.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Jan 22 at 20:44









          user26857

          39.3k124183




          39.3k124183










          answered Jan 22 at 17:43









          MaxMax

          15.2k11143




          15.2k11143












          • $begingroup$
            Oh yeah , Thanks.
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:44










          • $begingroup$
            Can u give me an example of a infinitely generated torsion abelian group? Does $mathbb{Z}_{2}^mathbb{N} work ?$
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:49












          • $begingroup$
            nevermind i understand it now
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:56


















          • $begingroup$
            Oh yeah , Thanks.
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:44










          • $begingroup$
            Can u give me an example of a infinitely generated torsion abelian group? Does $mathbb{Z}_{2}^mathbb{N} work ?$
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:49












          • $begingroup$
            nevermind i understand it now
            $endgroup$
            – Pedro Santos
            Jan 22 at 17:56
















          $begingroup$
          Oh yeah , Thanks.
          $endgroup$
          – Pedro Santos
          Jan 22 at 17:44




          $begingroup$
          Oh yeah , Thanks.
          $endgroup$
          – Pedro Santos
          Jan 22 at 17:44












          $begingroup$
          Can u give me an example of a infinitely generated torsion abelian group? Does $mathbb{Z}_{2}^mathbb{N} work ?$
          $endgroup$
          – Pedro Santos
          Jan 22 at 17:49






          $begingroup$
          Can u give me an example of a infinitely generated torsion abelian group? Does $mathbb{Z}_{2}^mathbb{N} work ?$
          $endgroup$
          – Pedro Santos
          Jan 22 at 17:49














          $begingroup$
          nevermind i understand it now
          $endgroup$
          – Pedro Santos
          Jan 22 at 17:56




          $begingroup$
          nevermind i understand it now
          $endgroup$
          – Pedro Santos
          Jan 22 at 17:56


















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