Every regular ideal contained in a maximal regular ideal?












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Let $A$ be a (not necessarily unital)commutative ring. We define a regular ideal $I$ if exists element $e in A$, such that $e$ is the unit in $A/I$.



Can we deduce, that every proper regular ideal is contained in a maximal regular ideal?





It seems that this is another Zorn's lemma argument: let $m_i$ be a chain of proper, regular ideals then $bigcup m_i$ is a proper ideal, but is it regular?










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    0












    $begingroup$


    Let $A$ be a (not necessarily unital)commutative ring. We define a regular ideal $I$ if exists element $e in A$, such that $e$ is the unit in $A/I$.



    Can we deduce, that every proper regular ideal is contained in a maximal regular ideal?





    It seems that this is another Zorn's lemma argument: let $m_i$ be a chain of proper, regular ideals then $bigcup m_i$ is a proper ideal, but is it regular?










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      Let $A$ be a (not necessarily unital)commutative ring. We define a regular ideal $I$ if exists element $e in A$, such that $e$ is the unit in $A/I$.



      Can we deduce, that every proper regular ideal is contained in a maximal regular ideal?





      It seems that this is another Zorn's lemma argument: let $m_i$ be a chain of proper, regular ideals then $bigcup m_i$ is a proper ideal, but is it regular?










      share|cite|improve this question









      $endgroup$




      Let $A$ be a (not necessarily unital)commutative ring. We define a regular ideal $I$ if exists element $e in A$, such that $e$ is the unit in $A/I$.



      Can we deduce, that every proper regular ideal is contained in a maximal regular ideal?





      It seems that this is another Zorn's lemma argument: let $m_i$ be a chain of proper, regular ideals then $bigcup m_i$ is a proper ideal, but is it regular?







      abstract-algebra ring-theory operator-theory






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      asked Dec 6 '18 at 9:17









      CL.CL.

      2,1992822




      2,1992822






















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          $begingroup$

          The set of ideals of $A/I$ is in bijection with the set of ideals of $A$ which contain $I$. Since $A/I$ is unital, there exists a maximal ideal in $A/I$ and this corresponds to a maximal ideal $J$ of $A$ containing $I$. Note that if $e in A$ is such that $e + I in A/I$ is the unit, then $e + J in A/J cong (A/I)/(J/I)$ is the unit, too. In fact, we have $ea - a, ae - a in I subseteq J$ for all $a in A$. Note that this shows that every ideal containing a regular ideal is already regular.






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            $begingroup$

            The set of ideals of $A/I$ is in bijection with the set of ideals of $A$ which contain $I$. Since $A/I$ is unital, there exists a maximal ideal in $A/I$ and this corresponds to a maximal ideal $J$ of $A$ containing $I$. Note that if $e in A$ is such that $e + I in A/I$ is the unit, then $e + J in A/J cong (A/I)/(J/I)$ is the unit, too. In fact, we have $ea - a, ae - a in I subseteq J$ for all $a in A$. Note that this shows that every ideal containing a regular ideal is already regular.






            share|cite|improve this answer









            $endgroup$


















              1












              $begingroup$

              The set of ideals of $A/I$ is in bijection with the set of ideals of $A$ which contain $I$. Since $A/I$ is unital, there exists a maximal ideal in $A/I$ and this corresponds to a maximal ideal $J$ of $A$ containing $I$. Note that if $e in A$ is such that $e + I in A/I$ is the unit, then $e + J in A/J cong (A/I)/(J/I)$ is the unit, too. In fact, we have $ea - a, ae - a in I subseteq J$ for all $a in A$. Note that this shows that every ideal containing a regular ideal is already regular.






              share|cite|improve this answer









              $endgroup$
















                1












                1








                1





                $begingroup$

                The set of ideals of $A/I$ is in bijection with the set of ideals of $A$ which contain $I$. Since $A/I$ is unital, there exists a maximal ideal in $A/I$ and this corresponds to a maximal ideal $J$ of $A$ containing $I$. Note that if $e in A$ is such that $e + I in A/I$ is the unit, then $e + J in A/J cong (A/I)/(J/I)$ is the unit, too. In fact, we have $ea - a, ae - a in I subseteq J$ for all $a in A$. Note that this shows that every ideal containing a regular ideal is already regular.






                share|cite|improve this answer









                $endgroup$



                The set of ideals of $A/I$ is in bijection with the set of ideals of $A$ which contain $I$. Since $A/I$ is unital, there exists a maximal ideal in $A/I$ and this corresponds to a maximal ideal $J$ of $A$ containing $I$. Note that if $e in A$ is such that $e + I in A/I$ is the unit, then $e + J in A/J cong (A/I)/(J/I)$ is the unit, too. In fact, we have $ea - a, ae - a in I subseteq J$ for all $a in A$. Note that this shows that every ideal containing a regular ideal is already regular.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Dec 6 '18 at 9:29









                Matthias KlupschMatthias Klupsch

                6,1591227




                6,1591227






























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