Show that $S^-1A = B$ for integral domains and $S = xin Asetminus0: x^-1in B$ [duplicate]

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Let $A subset B$ be commutative integral domains with $operatornameQuot(A) = operatornameQuot(B).$



Now consider the multiplicatively closed subset $S = xin Asetminus0: x^-1in B$.



I want to show that $S^-1A = B$. I would appreciate any help.







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marked as duplicate by Claude Leibovici, John Ma, max_zorn, Taroccoesbrocco, BLAZE Aug 4 at 5:09


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    Isn't $A = K[x,y]$, $B=K[x,y, y/x]$ a counter-example? As far as I can tell, it seems that $S = A^*$ in this case, so that $S^-1 A = A neq B$ in this case.
    – Marc Paul
    Jul 31 at 20:35














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  • Subrings of fraction fields [closed]

    4 answers



Let $A subset B$ be commutative integral domains with $operatornameQuot(A) = operatornameQuot(B).$



Now consider the multiplicatively closed subset $S = xin Asetminus0: x^-1in B$.



I want to show that $S^-1A = B$. I would appreciate any help.







share|cite|improve this question













marked as duplicate by Claude Leibovici, John Ma, max_zorn, Taroccoesbrocco, BLAZE Aug 4 at 5:09


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.










  • 1




    Isn't $A = K[x,y]$, $B=K[x,y, y/x]$ a counter-example? As far as I can tell, it seems that $S = A^*$ in this case, so that $S^-1 A = A neq B$ in this case.
    – Marc Paul
    Jul 31 at 20:35












up vote
1
down vote

favorite
1









up vote
1
down vote

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1






This question already has an answer here:



  • Subrings of fraction fields [closed]

    4 answers



Let $A subset B$ be commutative integral domains with $operatornameQuot(A) = operatornameQuot(B).$



Now consider the multiplicatively closed subset $S = xin Asetminus0: x^-1in B$.



I want to show that $S^-1A = B$. I would appreciate any help.







share|cite|improve this question














This question already has an answer here:



  • Subrings of fraction fields [closed]

    4 answers



Let $A subset B$ be commutative integral domains with $operatornameQuot(A) = operatornameQuot(B).$



Now consider the multiplicatively closed subset $S = xin Asetminus0: x^-1in B$.



I want to show that $S^-1A = B$. I would appreciate any help.





This question already has an answer here:



  • Subrings of fraction fields [closed]

    4 answers









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edited Jul 31 at 17:09









Bernard

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asked Jul 31 at 16:57









mathcourse

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marked as duplicate by Claude Leibovici, John Ma, max_zorn, Taroccoesbrocco, BLAZE Aug 4 at 5:09


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.






marked as duplicate by Claude Leibovici, John Ma, max_zorn, Taroccoesbrocco, BLAZE Aug 4 at 5:09


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.









  • 1




    Isn't $A = K[x,y]$, $B=K[x,y, y/x]$ a counter-example? As far as I can tell, it seems that $S = A^*$ in this case, so that $S^-1 A = A neq B$ in this case.
    – Marc Paul
    Jul 31 at 20:35












  • 1




    Isn't $A = K[x,y]$, $B=K[x,y, y/x]$ a counter-example? As far as I can tell, it seems that $S = A^*$ in this case, so that $S^-1 A = A neq B$ in this case.
    – Marc Paul
    Jul 31 at 20:35







1




1




Isn't $A = K[x,y]$, $B=K[x,y, y/x]$ a counter-example? As far as I can tell, it seems that $S = A^*$ in this case, so that $S^-1 A = A neq B$ in this case.
– Marc Paul
Jul 31 at 20:35




Isn't $A = K[x,y]$, $B=K[x,y, y/x]$ a counter-example? As far as I can tell, it seems that $S = A^*$ in this case, so that $S^-1 A = A neq B$ in this case.
– Marc Paul
Jul 31 at 20:35










1 Answer
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It suffices to prove $Bsubseteq S^-1A$, since we already have $Asubseteq Bsubseteq mathrmFrac(A)$.
For any $xin B$, $x=fracab$ for some $a,bin A$. By definition, correct.






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    1 Answer
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    1 Answer
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    active

    oldest

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    active

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    active

    oldest

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    up vote
    -1
    down vote













    It suffices to prove $Bsubseteq S^-1A$, since we already have $Asubseteq Bsubseteq mathrmFrac(A)$.
    For any $xin B$, $x=fracab$ for some $a,bin A$. By definition, correct.






    share|cite|improve this answer

























      up vote
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      down vote













      It suffices to prove $Bsubseteq S^-1A$, since we already have $Asubseteq Bsubseteq mathrmFrac(A)$.
      For any $xin B$, $x=fracab$ for some $a,bin A$. By definition, correct.






      share|cite|improve this answer























        up vote
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        down vote










        up vote
        -1
        down vote









        It suffices to prove $Bsubseteq S^-1A$, since we already have $Asubseteq Bsubseteq mathrmFrac(A)$.
        For any $xin B$, $x=fracab$ for some $a,bin A$. By definition, correct.






        share|cite|improve this answer













        It suffices to prove $Bsubseteq S^-1A$, since we already have $Asubseteq Bsubseteq mathrmFrac(A)$.
        For any $xin B$, $x=fracab$ for some $a,bin A$. By definition, correct.







        share|cite|improve this answer













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        share|cite|improve this answer











        answered Aug 1 at 20:25









        Li Guanyu

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