Is every ideal of Quotient Ring a PID?












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We are given a principal ideal domain $R$ and an ideal of this domain, $I$. Is it true that every proper ideal of $displaystylefrac{R}{I}$ a principal ideal domain ?



I have proven that every proper ideal, say, $overline{K}$ of $displaystylefrac{R}{I}$ is an ideal generated by an element of the $displaystylefrac{R}{I}$. Is it true that $overline{K}$ is an integral domain ?










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    1












    $begingroup$


    We are given a principal ideal domain $R$ and an ideal of this domain, $I$. Is it true that every proper ideal of $displaystylefrac{R}{I}$ a principal ideal domain ?



    I have proven that every proper ideal, say, $overline{K}$ of $displaystylefrac{R}{I}$ is an ideal generated by an element of the $displaystylefrac{R}{I}$. Is it true that $overline{K}$ is an integral domain ?










    share|cite|improve this question









    $endgroup$















      1












      1








      1


      2



      $begingroup$


      We are given a principal ideal domain $R$ and an ideal of this domain, $I$. Is it true that every proper ideal of $displaystylefrac{R}{I}$ a principal ideal domain ?



      I have proven that every proper ideal, say, $overline{K}$ of $displaystylefrac{R}{I}$ is an ideal generated by an element of the $displaystylefrac{R}{I}$. Is it true that $overline{K}$ is an integral domain ?










      share|cite|improve this question









      $endgroup$




      We are given a principal ideal domain $R$ and an ideal of this domain, $I$. Is it true that every proper ideal of $displaystylefrac{R}{I}$ a principal ideal domain ?



      I have proven that every proper ideal, say, $overline{K}$ of $displaystylefrac{R}{I}$ is an ideal generated by an element of the $displaystylefrac{R}{I}$. Is it true that $overline{K}$ is an integral domain ?







      abstract-algebra principal-ideal-domains






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      asked Jan 23 at 16:26









      Minto PMinto P

      667




      667






















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          $begingroup$

          No, in general $K$ can have zero divisors, and it will not always have an identity.



          For example: $mathbb Z/12mathbb Z$ and its ideal $6mathbb Z/12mathbb Z$ are examples for both.



          $K$ will not have zero divisors if $I$ is prime, but in a PID this would mean that $I={0}$ or else a maximal ideal, which are both pretty uninteresting cases.



          The best you can say is, as you concluded, that $R/I$ is always a principal ideal ring.






          share|cite|improve this answer











          $endgroup$





















            1












            $begingroup$

            Consider $mathbb{Z}$ and $p,q,r$, three prime integers. $mathbb{Z}/pqrmathbb{Z}$ is isomorphic to $mathbb{Z}/ptimesmathbb{Z}/qtimes mathbb{Z}/r$. $mathbb{Z}/ptimesmathbb{Z}/qtimes 0$ is a proper ideal of $mathbb{Z}/ptimesmathbb{Z}/qtimes mathbb{Z}/r$ and is not integral.






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              2 Answers
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              2 Answers
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              1












              $begingroup$

              No, in general $K$ can have zero divisors, and it will not always have an identity.



              For example: $mathbb Z/12mathbb Z$ and its ideal $6mathbb Z/12mathbb Z$ are examples for both.



              $K$ will not have zero divisors if $I$ is prime, but in a PID this would mean that $I={0}$ or else a maximal ideal, which are both pretty uninteresting cases.



              The best you can say is, as you concluded, that $R/I$ is always a principal ideal ring.






              share|cite|improve this answer











              $endgroup$


















                1












                $begingroup$

                No, in general $K$ can have zero divisors, and it will not always have an identity.



                For example: $mathbb Z/12mathbb Z$ and its ideal $6mathbb Z/12mathbb Z$ are examples for both.



                $K$ will not have zero divisors if $I$ is prime, but in a PID this would mean that $I={0}$ or else a maximal ideal, which are both pretty uninteresting cases.



                The best you can say is, as you concluded, that $R/I$ is always a principal ideal ring.






                share|cite|improve this answer











                $endgroup$
















                  1












                  1








                  1





                  $begingroup$

                  No, in general $K$ can have zero divisors, and it will not always have an identity.



                  For example: $mathbb Z/12mathbb Z$ and its ideal $6mathbb Z/12mathbb Z$ are examples for both.



                  $K$ will not have zero divisors if $I$ is prime, but in a PID this would mean that $I={0}$ or else a maximal ideal, which are both pretty uninteresting cases.



                  The best you can say is, as you concluded, that $R/I$ is always a principal ideal ring.






                  share|cite|improve this answer











                  $endgroup$



                  No, in general $K$ can have zero divisors, and it will not always have an identity.



                  For example: $mathbb Z/12mathbb Z$ and its ideal $6mathbb Z/12mathbb Z$ are examples for both.



                  $K$ will not have zero divisors if $I$ is prime, but in a PID this would mean that $I={0}$ or else a maximal ideal, which are both pretty uninteresting cases.



                  The best you can say is, as you concluded, that $R/I$ is always a principal ideal ring.







                  share|cite|improve this answer














                  share|cite|improve this answer



                  share|cite|improve this answer








                  edited Jan 23 at 16:58

























                  answered Jan 23 at 16:52









                  rschwiebrschwieb

                  107k12102251




                  107k12102251























                      1












                      $begingroup$

                      Consider $mathbb{Z}$ and $p,q,r$, three prime integers. $mathbb{Z}/pqrmathbb{Z}$ is isomorphic to $mathbb{Z}/ptimesmathbb{Z}/qtimes mathbb{Z}/r$. $mathbb{Z}/ptimesmathbb{Z}/qtimes 0$ is a proper ideal of $mathbb{Z}/ptimesmathbb{Z}/qtimes mathbb{Z}/r$ and is not integral.






                      share|cite|improve this answer











                      $endgroup$


















                        1












                        $begingroup$

                        Consider $mathbb{Z}$ and $p,q,r$, three prime integers. $mathbb{Z}/pqrmathbb{Z}$ is isomorphic to $mathbb{Z}/ptimesmathbb{Z}/qtimes mathbb{Z}/r$. $mathbb{Z}/ptimesmathbb{Z}/qtimes 0$ is a proper ideal of $mathbb{Z}/ptimesmathbb{Z}/qtimes mathbb{Z}/r$ and is not integral.






                        share|cite|improve this answer











                        $endgroup$
















                          1












                          1








                          1





                          $begingroup$

                          Consider $mathbb{Z}$ and $p,q,r$, three prime integers. $mathbb{Z}/pqrmathbb{Z}$ is isomorphic to $mathbb{Z}/ptimesmathbb{Z}/qtimes mathbb{Z}/r$. $mathbb{Z}/ptimesmathbb{Z}/qtimes 0$ is a proper ideal of $mathbb{Z}/ptimesmathbb{Z}/qtimes mathbb{Z}/r$ and is not integral.






                          share|cite|improve this answer











                          $endgroup$



                          Consider $mathbb{Z}$ and $p,q,r$, three prime integers. $mathbb{Z}/pqrmathbb{Z}$ is isomorphic to $mathbb{Z}/ptimesmathbb{Z}/qtimes mathbb{Z}/r$. $mathbb{Z}/ptimesmathbb{Z}/qtimes 0$ is a proper ideal of $mathbb{Z}/ptimesmathbb{Z}/qtimes mathbb{Z}/r$ and is not integral.







                          share|cite|improve this answer














                          share|cite|improve this answer



                          share|cite|improve this answer








                          edited Jan 23 at 19:19









                          J. W. Tanner

                          3,2401320




                          3,2401320










                          answered Jan 23 at 16:52









                          Tsemo AristideTsemo Aristide

                          59.4k11445




                          59.4k11445






























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