Determine the maximal ideals of $mathbb R^2$ by determining **all** its ideals.












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This is a letter of an exericse in Artin Algebra and has been asked and answered here as well as by Brian Bi here and Takumi Murayama here. I had a different approach here and have yet another approach.



enter image description here



$mathbb R$ is a field so its only ideals are $(1)$ and $(0)$. Thus, by Structure of ideals in the product of two rings all the ideals of $mathbb R^2$ are $$(0)times(0),(1)times(1),(0)times(1),(1)times(0)$$. Then it's obvious $$(0)times(1),(1)times(0)$$ are the maximal ideals.



Is this correct also?










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    4












    $begingroup$


    This is a letter of an exericse in Artin Algebra and has been asked and answered here as well as by Brian Bi here and Takumi Murayama here. I had a different approach here and have yet another approach.



    enter image description here



    $mathbb R$ is a field so its only ideals are $(1)$ and $(0)$. Thus, by Structure of ideals in the product of two rings all the ideals of $mathbb R^2$ are $$(0)times(0),(1)times(1),(0)times(1),(1)times(0)$$. Then it's obvious $$(0)times(1),(1)times(0)$$ are the maximal ideals.



    Is this correct also?










    share|cite|improve this question









    $endgroup$















      4












      4








      4





      $begingroup$


      This is a letter of an exericse in Artin Algebra and has been asked and answered here as well as by Brian Bi here and Takumi Murayama here. I had a different approach here and have yet another approach.



      enter image description here



      $mathbb R$ is a field so its only ideals are $(1)$ and $(0)$. Thus, by Structure of ideals in the product of two rings all the ideals of $mathbb R^2$ are $$(0)times(0),(1)times(1),(0)times(1),(1)times(0)$$. Then it's obvious $$(0)times(1),(1)times(0)$$ are the maximal ideals.



      Is this correct also?










      share|cite|improve this question









      $endgroup$




      This is a letter of an exericse in Artin Algebra and has been asked and answered here as well as by Brian Bi here and Takumi Murayama here. I had a different approach here and have yet another approach.



      enter image description here



      $mathbb R$ is a field so its only ideals are $(1)$ and $(0)$. Thus, by Structure of ideals in the product of two rings all the ideals of $mathbb R^2$ are $$(0)times(0),(1)times(1),(0)times(1),(1)times(0)$$. Then it's obvious $$(0)times(1),(1)times(0)$$ are the maximal ideals.



      Is this correct also?







      abstract-algebra proof-verification ring-theory ideals maximal-and-prime-ideals






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      asked Dec 29 '18 at 11:57







      user198044





























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          Yes, since $(1) times (1) = mathbb{R} times mathbb{R}$ is the whole ring and $(0) times (0)$ is contained in both $(0) times (1)$ and $(1) times (0)$. It is also clear that $(0) times (1) not subset (1) times (0)$ and vice versa.






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          • $begingroup$
            Thank you 0x539! I have to wait for 6-8 minutes to accept an answer.
            $endgroup$
            – user198044
            Dec 29 '18 at 12:04












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          1 Answer
          1






          active

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          active

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          active

          oldest

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          0












          $begingroup$

          Yes, since $(1) times (1) = mathbb{R} times mathbb{R}$ is the whole ring and $(0) times (0)$ is contained in both $(0) times (1)$ and $(1) times (0)$. It is also clear that $(0) times (1) not subset (1) times (0)$ and vice versa.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thank you 0x539! I have to wait for 6-8 minutes to accept an answer.
            $endgroup$
            – user198044
            Dec 29 '18 at 12:04
















          0












          $begingroup$

          Yes, since $(1) times (1) = mathbb{R} times mathbb{R}$ is the whole ring and $(0) times (0)$ is contained in both $(0) times (1)$ and $(1) times (0)$. It is also clear that $(0) times (1) not subset (1) times (0)$ and vice versa.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thank you 0x539! I have to wait for 6-8 minutes to accept an answer.
            $endgroup$
            – user198044
            Dec 29 '18 at 12:04














          0












          0








          0





          $begingroup$

          Yes, since $(1) times (1) = mathbb{R} times mathbb{R}$ is the whole ring and $(0) times (0)$ is contained in both $(0) times (1)$ and $(1) times (0)$. It is also clear that $(0) times (1) not subset (1) times (0)$ and vice versa.






          share|cite|improve this answer









          $endgroup$



          Yes, since $(1) times (1) = mathbb{R} times mathbb{R}$ is the whole ring and $(0) times (0)$ is contained in both $(0) times (1)$ and $(1) times (0)$. It is also clear that $(0) times (1) not subset (1) times (0)$ and vice versa.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 29 '18 at 12:02









          0x5390x539

          1,450518




          1,450518












          • $begingroup$
            Thank you 0x539! I have to wait for 6-8 minutes to accept an answer.
            $endgroup$
            – user198044
            Dec 29 '18 at 12:04


















          • $begingroup$
            Thank you 0x539! I have to wait for 6-8 minutes to accept an answer.
            $endgroup$
            – user198044
            Dec 29 '18 at 12:04
















          $begingroup$
          Thank you 0x539! I have to wait for 6-8 minutes to accept an answer.
          $endgroup$
          – user198044
          Dec 29 '18 at 12:04




          $begingroup$
          Thank you 0x539! I have to wait for 6-8 minutes to accept an answer.
          $endgroup$
          – user198044
          Dec 29 '18 at 12:04


















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