$I$ an irreducible ideal in a PID is a prime ideal












1












$begingroup$


$I$ is irreducible ideal of $R$ when $R$ is a PID , I want to show it's a prime ideal.



The definition I am familiar with: $I$ a proper ideal of $R$ is an irreducible ideal if for any two ideals $J,K$ such that $Isubseteq J$, $Isubseteq K$ , then $Ineq Jcap K$



Well denoting $I=langle arangle$ , Assuming $I$ is not a primes, means there are $x,yin R$ , such that $xyinlangle arangle$ such that $xnotinlangle a rangle$ , $ynotinlangle a rangle$.



Taking $langle x rangle cap langle y rangle$ , we get an ideal such that $ain langle x rangle cap langle y rangle$ because $a=xyin langle x rangle$ , $a=xyin langle y rangle$. So $langle a rangle subsetlangle x ranglecap langle y rangle$.



For $rin langle x ranglecap langle y rangle$
I tried to show $rin langle a rangle$ but didn't succeed, I gotthe next results:




  • $r = xd , r=ye Rightarrow r^2=xyed=acdot edRightarrow r^2 in langle a rangle$


  • $r=xd , r=ye Rightarrow ry=xyd=ad$ and$ rx=yxe=aeRightarrow rx,ryin langle a rangle$.










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$endgroup$












  • $begingroup$
    The question in the link talks about $ain$PID is irreducible $Leftrightarrow$ $a$ is prime. Yet I am asking about an irreducible Ideal, not about an irreducible element. Can someone please explain the equivalence (if exists)?
    $endgroup$
    – dan
    Jan 25 at 4:37


















1












$begingroup$


$I$ is irreducible ideal of $R$ when $R$ is a PID , I want to show it's a prime ideal.



The definition I am familiar with: $I$ a proper ideal of $R$ is an irreducible ideal if for any two ideals $J,K$ such that $Isubseteq J$, $Isubseteq K$ , then $Ineq Jcap K$



Well denoting $I=langle arangle$ , Assuming $I$ is not a primes, means there are $x,yin R$ , such that $xyinlangle arangle$ such that $xnotinlangle a rangle$ , $ynotinlangle a rangle$.



Taking $langle x rangle cap langle y rangle$ , we get an ideal such that $ain langle x rangle cap langle y rangle$ because $a=xyin langle x rangle$ , $a=xyin langle y rangle$. So $langle a rangle subsetlangle x ranglecap langle y rangle$.



For $rin langle x ranglecap langle y rangle$
I tried to show $rin langle a rangle$ but didn't succeed, I gotthe next results:




  • $r = xd , r=ye Rightarrow r^2=xyed=acdot edRightarrow r^2 in langle a rangle$


  • $r=xd , r=ye Rightarrow ry=xyd=ad$ and$ rx=yxe=aeRightarrow rx,ryin langle a rangle$.










share|cite|improve this question











$endgroup$












  • $begingroup$
    The question in the link talks about $ain$PID is irreducible $Leftrightarrow$ $a$ is prime. Yet I am asking about an irreducible Ideal, not about an irreducible element. Can someone please explain the equivalence (if exists)?
    $endgroup$
    – dan
    Jan 25 at 4:37
















1












1








1


2



$begingroup$


$I$ is irreducible ideal of $R$ when $R$ is a PID , I want to show it's a prime ideal.



The definition I am familiar with: $I$ a proper ideal of $R$ is an irreducible ideal if for any two ideals $J,K$ such that $Isubseteq J$, $Isubseteq K$ , then $Ineq Jcap K$



Well denoting $I=langle arangle$ , Assuming $I$ is not a primes, means there are $x,yin R$ , such that $xyinlangle arangle$ such that $xnotinlangle a rangle$ , $ynotinlangle a rangle$.



Taking $langle x rangle cap langle y rangle$ , we get an ideal such that $ain langle x rangle cap langle y rangle$ because $a=xyin langle x rangle$ , $a=xyin langle y rangle$. So $langle a rangle subsetlangle x ranglecap langle y rangle$.



For $rin langle x ranglecap langle y rangle$
I tried to show $rin langle a rangle$ but didn't succeed, I gotthe next results:




  • $r = xd , r=ye Rightarrow r^2=xyed=acdot edRightarrow r^2 in langle a rangle$


  • $r=xd , r=ye Rightarrow ry=xyd=ad$ and$ rx=yxe=aeRightarrow rx,ryin langle a rangle$.










share|cite|improve this question











$endgroup$




$I$ is irreducible ideal of $R$ when $R$ is a PID , I want to show it's a prime ideal.



The definition I am familiar with: $I$ a proper ideal of $R$ is an irreducible ideal if for any two ideals $J,K$ such that $Isubseteq J$, $Isubseteq K$ , then $Ineq Jcap K$



Well denoting $I=langle arangle$ , Assuming $I$ is not a primes, means there are $x,yin R$ , such that $xyinlangle arangle$ such that $xnotinlangle a rangle$ , $ynotinlangle a rangle$.



Taking $langle x rangle cap langle y rangle$ , we get an ideal such that $ain langle x rangle cap langle y rangle$ because $a=xyin langle x rangle$ , $a=xyin langle y rangle$. So $langle a rangle subsetlangle x ranglecap langle y rangle$.



For $rin langle x ranglecap langle y rangle$
I tried to show $rin langle a rangle$ but didn't succeed, I gotthe next results:




  • $r = xd , r=ye Rightarrow r^2=xyed=acdot edRightarrow r^2 in langle a rangle$


  • $r=xd , r=ye Rightarrow ry=xyd=ad$ and$ rx=yxe=aeRightarrow rx,ryin langle a rangle$.







abstract-algebra ring-theory ideals principal-ideal-domains






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edited Jan 25 at 10:02







dan

















asked Jan 24 at 18:08









dandan

607613




607613












  • $begingroup$
    The question in the link talks about $ain$PID is irreducible $Leftrightarrow$ $a$ is prime. Yet I am asking about an irreducible Ideal, not about an irreducible element. Can someone please explain the equivalence (if exists)?
    $endgroup$
    – dan
    Jan 25 at 4:37




















  • $begingroup$
    The question in the link talks about $ain$PID is irreducible $Leftrightarrow$ $a$ is prime. Yet I am asking about an irreducible Ideal, not about an irreducible element. Can someone please explain the equivalence (if exists)?
    $endgroup$
    – dan
    Jan 25 at 4:37


















$begingroup$
The question in the link talks about $ain$PID is irreducible $Leftrightarrow$ $a$ is prime. Yet I am asking about an irreducible Ideal, not about an irreducible element. Can someone please explain the equivalence (if exists)?
$endgroup$
– dan
Jan 25 at 4:37






$begingroup$
The question in the link talks about $ain$PID is irreducible $Leftrightarrow$ $a$ is prime. Yet I am asking about an irreducible Ideal, not about an irreducible element. Can someone please explain the equivalence (if exists)?
$endgroup$
– dan
Jan 25 at 4:37












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