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Math Help - Fields and gaussian integers

  1. #1
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    Fields and gaussian integers

    How many elements does the following field have? is u=1+i a primative element?

    \frac{Z[i]}{<2+3i>}

    I know that the norm of 2+3i =13, thus there will be 13 elements and this field will be isomorphic to GF(13), But i am not sure how to find the elements.
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  2. #2
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    Quote Originally Posted by ulysses123 View Post
    How many elements does the following field have? is u=1+i a primative element?

    \frac{Z[i]}{<2+3i>}

    I know that the norm of 2+3i =13, thus there will be 13 elements and this field will be isomorphic to GF(13), But i am not sure how to find the elements.
    Do as you do to find the elements of a ring of fractions of a polynomial ring divided by the principal

    ideal generated by an irreducible pol.:

    1) Divide any element w=\alpha+\beta i\in\mathbb{Z}[i] by 2+3i with remainder (why is this possible?)

    2) If \alpha+\beta i=(a+bi)(2+3i)+r\,,\,\,r=c+di\in\mathbb{Z}[i]\,,\,\,r=0\,\,or\,\,c^2+d^2<2^2+3^2=13 , then
    \alpha+\beta i\cong  r\!\!\pmod{<2+3i>} ...

    3) Deduce from the above that every element in the quotient ring can be represented by an element with norm < 13 or zero.

    Tonio
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  3. #3
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    every element can be represented by one with norm <13, but we dont have to take this representation do we?
    Using the element 2+3i and then rotating it by 90 degrees i formed a square with these two vectors then took all the elements in it as my represenatives, then using the element 1+i and generating its powers i found that it only has order 4.However for the second field i havnt been able to deduce if 1+i is a generator because one of the powers gives me an element thats not in the field or any of the representative cosets.So now i'm getting confused.
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