Non-zero Ideal in an Integral Domain is indecomposable











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Need to prove that : any non-zero ideal in an integral domain is indecomposable.



Now if $I=Abigoplus B$, then $A$ and $B$ are subgroups of $I$, if I am not wrong. Does it say anything about having idempotents, then in that case multiplication of the two idempotents will be zero leading to a contradiction that we are in a domain. Please help.










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  • The decomposition of an ideal doesn’t always have anything to do with idempotents. In a domain, there are only trivial idempotents. There are noncommutative domains in which there are right ideals with infinitely many nonzero summands.
    – rschwieb
    Nov 17 at 19:22

















up vote
1
down vote

favorite












Need to prove that : any non-zero ideal in an integral domain is indecomposable.



Now if $I=Abigoplus B$, then $A$ and $B$ are subgroups of $I$, if I am not wrong. Does it say anything about having idempotents, then in that case multiplication of the two idempotents will be zero leading to a contradiction that we are in a domain. Please help.










share|cite|improve this question
























  • The decomposition of an ideal doesn’t always have anything to do with idempotents. In a domain, there are only trivial idempotents. There are noncommutative domains in which there are right ideals with infinitely many nonzero summands.
    – rschwieb
    Nov 17 at 19:22















up vote
1
down vote

favorite









up vote
1
down vote

favorite











Need to prove that : any non-zero ideal in an integral domain is indecomposable.



Now if $I=Abigoplus B$, then $A$ and $B$ are subgroups of $I$, if I am not wrong. Does it say anything about having idempotents, then in that case multiplication of the two idempotents will be zero leading to a contradiction that we are in a domain. Please help.










share|cite|improve this question















Need to prove that : any non-zero ideal in an integral domain is indecomposable.



Now if $I=Abigoplus B$, then $A$ and $B$ are subgroups of $I$, if I am not wrong. Does it say anything about having idempotents, then in that case multiplication of the two idempotents will be zero leading to a contradiction that we are in a domain. Please help.







abstract-algebra ring-theory ideals integral-domain






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edited Nov 17 at 17:48

























asked Nov 17 at 17:12









PSG

1999




1999












  • The decomposition of an ideal doesn’t always have anything to do with idempotents. In a domain, there are only trivial idempotents. There are noncommutative domains in which there are right ideals with infinitely many nonzero summands.
    – rschwieb
    Nov 17 at 19:22




















  • The decomposition of an ideal doesn’t always have anything to do with idempotents. In a domain, there are only trivial idempotents. There are noncommutative domains in which there are right ideals with infinitely many nonzero summands.
    – rschwieb
    Nov 17 at 19:22


















The decomposition of an ideal doesn’t always have anything to do with idempotents. In a domain, there are only trivial idempotents. There are noncommutative domains in which there are right ideals with infinitely many nonzero summands.
– rschwieb
Nov 17 at 19:22






The decomposition of an ideal doesn’t always have anything to do with idempotents. In a domain, there are only trivial idempotents. There are noncommutative domains in which there are right ideals with infinitely many nonzero summands.
– rschwieb
Nov 17 at 19:22












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$Acap Bsupseteq ABneq {0}$ If $A$ and $B$ are nonzero.






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    accepted










    $Acap Bsupseteq ABneq {0}$ If $A$ and $B$ are nonzero.






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      up vote
      1
      down vote



      accepted










      $Acap Bsupseteq ABneq {0}$ If $A$ and $B$ are nonzero.






      share|cite|improve this answer























        up vote
        1
        down vote



        accepted







        up vote
        1
        down vote



        accepted






        $Acap Bsupseteq ABneq {0}$ If $A$ and $B$ are nonzero.






        share|cite|improve this answer












        $Acap Bsupseteq ABneq {0}$ If $A$ and $B$ are nonzero.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Nov 17 at 18:37









        rschwieb

        103k1299238




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