Why $2mathbbZ $ is not integral domain?

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I know that $mathbbZ$ is an integral domain .if $ca = cb$, where $a, b, c in Z$ and $c neq 0$...



Now my Question is that Why $2mathbbZ $ is not integral domain ?



pliz help me,,,,



thanks u







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    up vote
    -2
    down vote

    favorite












    I know that $mathbbZ$ is an integral domain .if $ca = cb$, where $a, b, c in Z$ and $c neq 0$...



    Now my Question is that Why $2mathbbZ $ is not integral domain ?



    pliz help me,,,,



    thanks u







    share|cite|improve this question























      up vote
      -2
      down vote

      favorite









      up vote
      -2
      down vote

      favorite











      I know that $mathbbZ$ is an integral domain .if $ca = cb$, where $a, b, c in Z$ and $c neq 0$...



      Now my Question is that Why $2mathbbZ $ is not integral domain ?



      pliz help me,,,,



      thanks u







      share|cite|improve this question













      I know that $mathbbZ$ is an integral domain .if $ca = cb$, where $a, b, c in Z$ and $c neq 0$...



      Now my Question is that Why $2mathbbZ $ is not integral domain ?



      pliz help me,,,,



      thanks u









      share|cite|improve this question












      share|cite|improve this question




      share|cite|improve this question








      edited Jul 16 at 9:32









      Bernard

      110k635103




      110k635103









      asked Jul 16 at 9:14









      stupid

      57319




      57319




















          2 Answers
          2






          active

          oldest

          votes

















          up vote
          2
          down vote













          In commutative ring theory, we generally require that a ring contains a multiplicative identity element. Such an element is not contained in $2Bbb Z$, so we wouldn't consider it a ring, and therefore not an integral domain.



          If your ring theory does not require a multiplicative identity, then $2Bbb Z$ is a ring. In that case, it would also be an integral domain.






          share|cite|improve this answer





















          • Hmm I'm confused... why are there so many definitions for rings/integral domains? In Dummit & Foote where I learned, $2mathbbZ$ would be a ring and not an integral domain, because it doesn't have an identity. If someone is talking about rings, how can I know which definition they're using?
            – Ovi
            Jul 16 at 9:35






          • 2




            @Ovi If they don't tell you, you can't know which definition they're using. That's just the way it is, sorry. Some times you may be able to glean from context, but that's it. As for why there are so many definitions, that's just what happens when a field is developed independently by many mathematicians, none of whom know what will actually turn out to be important in the end.
            – Arthur
            Jul 16 at 9:36











          • Oh I thought there may be a standard definition which the majority of people use, because everything I've read on stackexcahgen is consistent with the definitions I got from Dummit & Foote
            – Ovi
            Jul 16 at 9:38

















          up vote
          1
          down vote













          It depends if you want to have an identity - if you insist on having then it isn't, otherwise it is.



          Here's a useful link: https://www.quora.com/Is-2Z-an-integral-domain






          share|cite|improve this answer





















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            2 Answers
            2






            active

            oldest

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            2 Answers
            2






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            2
            down vote













            In commutative ring theory, we generally require that a ring contains a multiplicative identity element. Such an element is not contained in $2Bbb Z$, so we wouldn't consider it a ring, and therefore not an integral domain.



            If your ring theory does not require a multiplicative identity, then $2Bbb Z$ is a ring. In that case, it would also be an integral domain.






            share|cite|improve this answer





















            • Hmm I'm confused... why are there so many definitions for rings/integral domains? In Dummit & Foote where I learned, $2mathbbZ$ would be a ring and not an integral domain, because it doesn't have an identity. If someone is talking about rings, how can I know which definition they're using?
              – Ovi
              Jul 16 at 9:35






            • 2




              @Ovi If they don't tell you, you can't know which definition they're using. That's just the way it is, sorry. Some times you may be able to glean from context, but that's it. As for why there are so many definitions, that's just what happens when a field is developed independently by many mathematicians, none of whom know what will actually turn out to be important in the end.
              – Arthur
              Jul 16 at 9:36











            • Oh I thought there may be a standard definition which the majority of people use, because everything I've read on stackexcahgen is consistent with the definitions I got from Dummit & Foote
              – Ovi
              Jul 16 at 9:38














            up vote
            2
            down vote













            In commutative ring theory, we generally require that a ring contains a multiplicative identity element. Such an element is not contained in $2Bbb Z$, so we wouldn't consider it a ring, and therefore not an integral domain.



            If your ring theory does not require a multiplicative identity, then $2Bbb Z$ is a ring. In that case, it would also be an integral domain.






            share|cite|improve this answer





















            • Hmm I'm confused... why are there so many definitions for rings/integral domains? In Dummit & Foote where I learned, $2mathbbZ$ would be a ring and not an integral domain, because it doesn't have an identity. If someone is talking about rings, how can I know which definition they're using?
              – Ovi
              Jul 16 at 9:35






            • 2




              @Ovi If they don't tell you, you can't know which definition they're using. That's just the way it is, sorry. Some times you may be able to glean from context, but that's it. As for why there are so many definitions, that's just what happens when a field is developed independently by many mathematicians, none of whom know what will actually turn out to be important in the end.
              – Arthur
              Jul 16 at 9:36











            • Oh I thought there may be a standard definition which the majority of people use, because everything I've read on stackexcahgen is consistent with the definitions I got from Dummit & Foote
              – Ovi
              Jul 16 at 9:38












            up vote
            2
            down vote










            up vote
            2
            down vote









            In commutative ring theory, we generally require that a ring contains a multiplicative identity element. Such an element is not contained in $2Bbb Z$, so we wouldn't consider it a ring, and therefore not an integral domain.



            If your ring theory does not require a multiplicative identity, then $2Bbb Z$ is a ring. In that case, it would also be an integral domain.






            share|cite|improve this answer













            In commutative ring theory, we generally require that a ring contains a multiplicative identity element. Such an element is not contained in $2Bbb Z$, so we wouldn't consider it a ring, and therefore not an integral domain.



            If your ring theory does not require a multiplicative identity, then $2Bbb Z$ is a ring. In that case, it would also be an integral domain.







            share|cite|improve this answer













            share|cite|improve this answer



            share|cite|improve this answer











            answered Jul 16 at 9:18









            Arthur

            98.9k793175




            98.9k793175











            • Hmm I'm confused... why are there so many definitions for rings/integral domains? In Dummit & Foote where I learned, $2mathbbZ$ would be a ring and not an integral domain, because it doesn't have an identity. If someone is talking about rings, how can I know which definition they're using?
              – Ovi
              Jul 16 at 9:35






            • 2




              @Ovi If they don't tell you, you can't know which definition they're using. That's just the way it is, sorry. Some times you may be able to glean from context, but that's it. As for why there are so many definitions, that's just what happens when a field is developed independently by many mathematicians, none of whom know what will actually turn out to be important in the end.
              – Arthur
              Jul 16 at 9:36











            • Oh I thought there may be a standard definition which the majority of people use, because everything I've read on stackexcahgen is consistent with the definitions I got from Dummit & Foote
              – Ovi
              Jul 16 at 9:38
















            • Hmm I'm confused... why are there so many definitions for rings/integral domains? In Dummit & Foote where I learned, $2mathbbZ$ would be a ring and not an integral domain, because it doesn't have an identity. If someone is talking about rings, how can I know which definition they're using?
              – Ovi
              Jul 16 at 9:35






            • 2




              @Ovi If they don't tell you, you can't know which definition they're using. That's just the way it is, sorry. Some times you may be able to glean from context, but that's it. As for why there are so many definitions, that's just what happens when a field is developed independently by many mathematicians, none of whom know what will actually turn out to be important in the end.
              – Arthur
              Jul 16 at 9:36











            • Oh I thought there may be a standard definition which the majority of people use, because everything I've read on stackexcahgen is consistent with the definitions I got from Dummit & Foote
              – Ovi
              Jul 16 at 9:38















            Hmm I'm confused... why are there so many definitions for rings/integral domains? In Dummit & Foote where I learned, $2mathbbZ$ would be a ring and not an integral domain, because it doesn't have an identity. If someone is talking about rings, how can I know which definition they're using?
            – Ovi
            Jul 16 at 9:35




            Hmm I'm confused... why are there so many definitions for rings/integral domains? In Dummit & Foote where I learned, $2mathbbZ$ would be a ring and not an integral domain, because it doesn't have an identity. If someone is talking about rings, how can I know which definition they're using?
            – Ovi
            Jul 16 at 9:35




            2




            2




            @Ovi If they don't tell you, you can't know which definition they're using. That's just the way it is, sorry. Some times you may be able to glean from context, but that's it. As for why there are so many definitions, that's just what happens when a field is developed independently by many mathematicians, none of whom know what will actually turn out to be important in the end.
            – Arthur
            Jul 16 at 9:36





            @Ovi If they don't tell you, you can't know which definition they're using. That's just the way it is, sorry. Some times you may be able to glean from context, but that's it. As for why there are so many definitions, that's just what happens when a field is developed independently by many mathematicians, none of whom know what will actually turn out to be important in the end.
            – Arthur
            Jul 16 at 9:36













            Oh I thought there may be a standard definition which the majority of people use, because everything I've read on stackexcahgen is consistent with the definitions I got from Dummit & Foote
            – Ovi
            Jul 16 at 9:38




            Oh I thought there may be a standard definition which the majority of people use, because everything I've read on stackexcahgen is consistent with the definitions I got from Dummit & Foote
            – Ovi
            Jul 16 at 9:38










            up vote
            1
            down vote













            It depends if you want to have an identity - if you insist on having then it isn't, otherwise it is.



            Here's a useful link: https://www.quora.com/Is-2Z-an-integral-domain






            share|cite|improve this answer

























              up vote
              1
              down vote













              It depends if you want to have an identity - if you insist on having then it isn't, otherwise it is.



              Here's a useful link: https://www.quora.com/Is-2Z-an-integral-domain






              share|cite|improve this answer























                up vote
                1
                down vote










                up vote
                1
                down vote









                It depends if you want to have an identity - if you insist on having then it isn't, otherwise it is.



                Here's a useful link: https://www.quora.com/Is-2Z-an-integral-domain






                share|cite|improve this answer













                It depends if you want to have an identity - if you insist on having then it isn't, otherwise it is.



                Here's a useful link: https://www.quora.com/Is-2Z-an-integral-domain







                share|cite|improve this answer













                share|cite|improve this answer



                share|cite|improve this answer











                answered Jul 16 at 9:18









                asdf

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