Why are real and complex numbers consider rings when irrationals aren't? [closed]











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Irrational numbers are not closed under multiplication, then why are real and complex numbers considered rings? Aren't real and complex numbers supposed to have irrational numbers?



*Made the mistake of thinking if subsets were to be invalid, the higher sets would be invalid too. Thanks to @Zachary Selk for clarify it!










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closed as unclear what you're asking by Bungo, Morgan Rodgers, José Carlos Santos, amWhy, rschwieb Nov 16 at 12:02


Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.















  • Irrationals are not closed under addition/multiplication.
    – Lord Shark the Unknown
    Nov 16 at 5:51






  • 3




    You seem to be arguing that if $A$ is not a ring and $Asubset B$ then $B$ is not a ring. This is not correct.
    – MPW
    Nov 16 at 6:24










  • Using the operations of the real numbers, the product of two irrationals isn't necessarily irrational, the sum of two irrationals isn't necessarily irrational, and there is no irrational additive identity, so the set of irrational numbers wildly fails the criteria for being a subring of $mathbb R$. Of course, you could make them into a ring with some weird product, but that isn't apparently what you're talking about.
    – rschwieb
    Nov 16 at 19:52















up vote
-1
down vote

favorite












Irrational numbers are not closed under multiplication, then why are real and complex numbers considered rings? Aren't real and complex numbers supposed to have irrational numbers?



*Made the mistake of thinking if subsets were to be invalid, the higher sets would be invalid too. Thanks to @Zachary Selk for clarify it!










share|cite|improve this question















closed as unclear what you're asking by Bungo, Morgan Rodgers, José Carlos Santos, amWhy, rschwieb Nov 16 at 12:02


Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.















  • Irrationals are not closed under addition/multiplication.
    – Lord Shark the Unknown
    Nov 16 at 5:51






  • 3




    You seem to be arguing that if $A$ is not a ring and $Asubset B$ then $B$ is not a ring. This is not correct.
    – MPW
    Nov 16 at 6:24










  • Using the operations of the real numbers, the product of two irrationals isn't necessarily irrational, the sum of two irrationals isn't necessarily irrational, and there is no irrational additive identity, so the set of irrational numbers wildly fails the criteria for being a subring of $mathbb R$. Of course, you could make them into a ring with some weird product, but that isn't apparently what you're talking about.
    – rschwieb
    Nov 16 at 19:52













up vote
-1
down vote

favorite









up vote
-1
down vote

favorite











Irrational numbers are not closed under multiplication, then why are real and complex numbers considered rings? Aren't real and complex numbers supposed to have irrational numbers?



*Made the mistake of thinking if subsets were to be invalid, the higher sets would be invalid too. Thanks to @Zachary Selk for clarify it!










share|cite|improve this question















Irrational numbers are not closed under multiplication, then why are real and complex numbers considered rings? Aren't real and complex numbers supposed to have irrational numbers?



*Made the mistake of thinking if subsets were to be invalid, the higher sets would be invalid too. Thanks to @Zachary Selk for clarify it!







abstract-algebra ring-theory






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edited Nov 17 at 5:02

























asked Nov 16 at 5:49









John

12




12




closed as unclear what you're asking by Bungo, Morgan Rodgers, José Carlos Santos, amWhy, rschwieb Nov 16 at 12:02


Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.






closed as unclear what you're asking by Bungo, Morgan Rodgers, José Carlos Santos, amWhy, rschwieb Nov 16 at 12:02


Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.














  • Irrationals are not closed under addition/multiplication.
    – Lord Shark the Unknown
    Nov 16 at 5:51






  • 3




    You seem to be arguing that if $A$ is not a ring and $Asubset B$ then $B$ is not a ring. This is not correct.
    – MPW
    Nov 16 at 6:24










  • Using the operations of the real numbers, the product of two irrationals isn't necessarily irrational, the sum of two irrationals isn't necessarily irrational, and there is no irrational additive identity, so the set of irrational numbers wildly fails the criteria for being a subring of $mathbb R$. Of course, you could make them into a ring with some weird product, but that isn't apparently what you're talking about.
    – rschwieb
    Nov 16 at 19:52


















  • Irrationals are not closed under addition/multiplication.
    – Lord Shark the Unknown
    Nov 16 at 5:51






  • 3




    You seem to be arguing that if $A$ is not a ring and $Asubset B$ then $B$ is not a ring. This is not correct.
    – MPW
    Nov 16 at 6:24










  • Using the operations of the real numbers, the product of two irrationals isn't necessarily irrational, the sum of two irrationals isn't necessarily irrational, and there is no irrational additive identity, so the set of irrational numbers wildly fails the criteria for being a subring of $mathbb R$. Of course, you could make them into a ring with some weird product, but that isn't apparently what you're talking about.
    – rschwieb
    Nov 16 at 19:52
















Irrationals are not closed under addition/multiplication.
– Lord Shark the Unknown
Nov 16 at 5:51




Irrationals are not closed under addition/multiplication.
– Lord Shark the Unknown
Nov 16 at 5:51




3




3




You seem to be arguing that if $A$ is not a ring and $Asubset B$ then $B$ is not a ring. This is not correct.
– MPW
Nov 16 at 6:24




You seem to be arguing that if $A$ is not a ring and $Asubset B$ then $B$ is not a ring. This is not correct.
– MPW
Nov 16 at 6:24












Using the operations of the real numbers, the product of two irrationals isn't necessarily irrational, the sum of two irrationals isn't necessarily irrational, and there is no irrational additive identity, so the set of irrational numbers wildly fails the criteria for being a subring of $mathbb R$. Of course, you could make them into a ring with some weird product, but that isn't apparently what you're talking about.
– rschwieb
Nov 16 at 19:52




Using the operations of the real numbers, the product of two irrationals isn't necessarily irrational, the sum of two irrationals isn't necessarily irrational, and there is no irrational additive identity, so the set of irrational numbers wildly fails the criteria for being a subring of $mathbb R$. Of course, you could make them into a ring with some weird product, but that isn't apparently what you're talking about.
– rschwieb
Nov 16 at 19:52










3 Answers
3






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3
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The irrationals are not closed under multiplication, but the reals and complex numbers are. Why should the irrationals not being closed matter to whether the reals and complex numbers are rings? ${2}$ is not closed under multiplication (or addition), but it is a subset of the integers, which form a ring.






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    up vote
    1
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    Yes, real numbers do indeed contain irrational numbers. However, the only thing irrationals can "escape to" are rationals, i.e. reals. So reals are a ring.



    As a matter of fact, every nonzero ring contains a subset that is not a ring.






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    • Yea, I made the mistake of thinking if a subset is invalid, the higher set would be too. Sort of a bad question on my part but thanks for the simple explanation. This answers my question best, thanks.
      – John
      Nov 17 at 5:00


















    up vote
    0
    down vote













    Well, the irrationals are not closed under multiplication, e.g., $sqrt 2 cdot sqrt 2 = 2$. And what would be the zero and unit elements?



    However, what is interesting is that one can define a ring structure on the set ${Bbb I}$ of irrational numbers by using (any) bijection $phi:{Bbb I}rightarrow{Bbb R}$.






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      3 Answers
      3






      active

      oldest

      votes








      3 Answers
      3






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes








      up vote
      3
      down vote













      The irrationals are not closed under multiplication, but the reals and complex numbers are. Why should the irrationals not being closed matter to whether the reals and complex numbers are rings? ${2}$ is not closed under multiplication (or addition), but it is a subset of the integers, which form a ring.






      share|cite|improve this answer

























        up vote
        3
        down vote













        The irrationals are not closed under multiplication, but the reals and complex numbers are. Why should the irrationals not being closed matter to whether the reals and complex numbers are rings? ${2}$ is not closed under multiplication (or addition), but it is a subset of the integers, which form a ring.






        share|cite|improve this answer























          up vote
          3
          down vote










          up vote
          3
          down vote









          The irrationals are not closed under multiplication, but the reals and complex numbers are. Why should the irrationals not being closed matter to whether the reals and complex numbers are rings? ${2}$ is not closed under multiplication (or addition), but it is a subset of the integers, which form a ring.






          share|cite|improve this answer












          The irrationals are not closed under multiplication, but the reals and complex numbers are. Why should the irrationals not being closed matter to whether the reals and complex numbers are rings? ${2}$ is not closed under multiplication (or addition), but it is a subset of the integers, which form a ring.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Nov 16 at 5:51









          Ross Millikan

          287k23195364




          287k23195364






















              up vote
              1
              down vote













              Yes, real numbers do indeed contain irrational numbers. However, the only thing irrationals can "escape to" are rationals, i.e. reals. So reals are a ring.



              As a matter of fact, every nonzero ring contains a subset that is not a ring.






              share|cite|improve this answer





















              • Yea, I made the mistake of thinking if a subset is invalid, the higher set would be too. Sort of a bad question on my part but thanks for the simple explanation. This answers my question best, thanks.
                – John
                Nov 17 at 5:00















              up vote
              1
              down vote













              Yes, real numbers do indeed contain irrational numbers. However, the only thing irrationals can "escape to" are rationals, i.e. reals. So reals are a ring.



              As a matter of fact, every nonzero ring contains a subset that is not a ring.






              share|cite|improve this answer





















              • Yea, I made the mistake of thinking if a subset is invalid, the higher set would be too. Sort of a bad question on my part but thanks for the simple explanation. This answers my question best, thanks.
                – John
                Nov 17 at 5:00













              up vote
              1
              down vote










              up vote
              1
              down vote









              Yes, real numbers do indeed contain irrational numbers. However, the only thing irrationals can "escape to" are rationals, i.e. reals. So reals are a ring.



              As a matter of fact, every nonzero ring contains a subset that is not a ring.






              share|cite|improve this answer












              Yes, real numbers do indeed contain irrational numbers. However, the only thing irrationals can "escape to" are rationals, i.e. reals. So reals are a ring.



              As a matter of fact, every nonzero ring contains a subset that is not a ring.







              share|cite|improve this answer












              share|cite|improve this answer



              share|cite|improve this answer










              answered Nov 16 at 5:55









              Zachary Selk

              412211




              412211












              • Yea, I made the mistake of thinking if a subset is invalid, the higher set would be too. Sort of a bad question on my part but thanks for the simple explanation. This answers my question best, thanks.
                – John
                Nov 17 at 5:00


















              • Yea, I made the mistake of thinking if a subset is invalid, the higher set would be too. Sort of a bad question on my part but thanks for the simple explanation. This answers my question best, thanks.
                – John
                Nov 17 at 5:00
















              Yea, I made the mistake of thinking if a subset is invalid, the higher set would be too. Sort of a bad question on my part but thanks for the simple explanation. This answers my question best, thanks.
              – John
              Nov 17 at 5:00




              Yea, I made the mistake of thinking if a subset is invalid, the higher set would be too. Sort of a bad question on my part but thanks for the simple explanation. This answers my question best, thanks.
              – John
              Nov 17 at 5:00










              up vote
              0
              down vote













              Well, the irrationals are not closed under multiplication, e.g., $sqrt 2 cdot sqrt 2 = 2$. And what would be the zero and unit elements?



              However, what is interesting is that one can define a ring structure on the set ${Bbb I}$ of irrational numbers by using (any) bijection $phi:{Bbb I}rightarrow{Bbb R}$.






              share|cite|improve this answer



























                up vote
                0
                down vote













                Well, the irrationals are not closed under multiplication, e.g., $sqrt 2 cdot sqrt 2 = 2$. And what would be the zero and unit elements?



                However, what is interesting is that one can define a ring structure on the set ${Bbb I}$ of irrational numbers by using (any) bijection $phi:{Bbb I}rightarrow{Bbb R}$.






                share|cite|improve this answer

























                  up vote
                  0
                  down vote










                  up vote
                  0
                  down vote









                  Well, the irrationals are not closed under multiplication, e.g., $sqrt 2 cdot sqrt 2 = 2$. And what would be the zero and unit elements?



                  However, what is interesting is that one can define a ring structure on the set ${Bbb I}$ of irrational numbers by using (any) bijection $phi:{Bbb I}rightarrow{Bbb R}$.






                  share|cite|improve this answer














                  Well, the irrationals are not closed under multiplication, e.g., $sqrt 2 cdot sqrt 2 = 2$. And what would be the zero and unit elements?



                  However, what is interesting is that one can define a ring structure on the set ${Bbb I}$ of irrational numbers by using (any) bijection $phi:{Bbb I}rightarrow{Bbb R}$.







                  share|cite|improve this answer














                  share|cite|improve this answer



                  share|cite|improve this answer








                  edited Nov 16 at 8:47

























                  answered Nov 16 at 6:33









                  Wuestenfux

                  2,4791410




                  2,4791410















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