What will be the smallest ring containing two rings?

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Let $A$ be a commutative ring with $1$. Suppose $R$ and $S$ are two subrings of $A$ containing the same multiplicative unity. Then what is the description of the smallest ring containing $R$ and $S$ inside $A$ ?



In addition if $R$ and $S$ are domains can we say that the smallest ring containing them is also a domain?




I need some explanations to this. Thank you.










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    5












    $begingroup$



    Let $A$ be a commutative ring with $1$. Suppose $R$ and $S$ are two subrings of $A$ containing the same multiplicative unity. Then what is the description of the smallest ring containing $R$ and $S$ inside $A$ ?



    In addition if $R$ and $S$ are domains can we say that the smallest ring containing them is also a domain?




    I need some explanations to this. Thank you.










    share|cite|improve this question











    $endgroup$














      5












      5








      5


      1



      $begingroup$



      Let $A$ be a commutative ring with $1$. Suppose $R$ and $S$ are two subrings of $A$ containing the same multiplicative unity. Then what is the description of the smallest ring containing $R$ and $S$ inside $A$ ?



      In addition if $R$ and $S$ are domains can we say that the smallest ring containing them is also a domain?




      I need some explanations to this. Thank you.










      share|cite|improve this question











      $endgroup$





      Let $A$ be a commutative ring with $1$. Suppose $R$ and $S$ are two subrings of $A$ containing the same multiplicative unity. Then what is the description of the smallest ring containing $R$ and $S$ inside $A$ ?



      In addition if $R$ and $S$ are domains can we say that the smallest ring containing them is also a domain?




      I need some explanations to this. Thank you.







      abstract-algebra ring-theory commutative-algebra integral-domain






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      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Jan 3 at 14:34







      user593746

















      asked Jan 3 at 10:50









      user371231user371231

      771511




      771511




















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          The smallest ring containing both $R$ and $S$ is the set
          $$ leftsum_i=1^n r_is_i Bigg. $$



          Even if $R$ and $S$ are domains, this ring does not have to be a domain: take $A=mathbbZ[x,y]/(xy)$, $R= mathbbZ[x]$ and $S = mathbbZ[y]$.






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            1 Answer
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            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            6












            $begingroup$

            The smallest ring containing both $R$ and $S$ is the set
            $$ leftsum_i=1^n r_is_i Bigg. $$



            Even if $R$ and $S$ are domains, this ring does not have to be a domain: take $A=mathbbZ[x,y]/(xy)$, $R= mathbbZ[x]$ and $S = mathbbZ[y]$.






            share|cite|improve this answer











            $endgroup$

















              6












              $begingroup$

              The smallest ring containing both $R$ and $S$ is the set
              $$ leftsum_i=1^n r_is_i Bigg. $$



              Even if $R$ and $S$ are domains, this ring does not have to be a domain: take $A=mathbbZ[x,y]/(xy)$, $R= mathbbZ[x]$ and $S = mathbbZ[y]$.






              share|cite|improve this answer











              $endgroup$















                6












                6








                6





                $begingroup$

                The smallest ring containing both $R$ and $S$ is the set
                $$ leftsum_i=1^n r_is_i Bigg. $$



                Even if $R$ and $S$ are domains, this ring does not have to be a domain: take $A=mathbbZ[x,y]/(xy)$, $R= mathbbZ[x]$ and $S = mathbbZ[y]$.






                share|cite|improve this answer











                $endgroup$



                The smallest ring containing both $R$ and $S$ is the set
                $$ leftsum_i=1^n r_is_i Bigg. $$



                Even if $R$ and $S$ are domains, this ring does not have to be a domain: take $A=mathbbZ[x,y]/(xy)$, $R= mathbbZ[x]$ and $S = mathbbZ[y]$.







                share|cite|improve this answer














                share|cite|improve this answer



                share|cite|improve this answer








                edited Jan 3 at 14:35







                user593746

















                answered Jan 3 at 10:59









                Pierre-Guy PlamondonPierre-Guy Plamondon

                8,79511639




                8,79511639



























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