absolute value and valuation on the field of formal power series

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I'm currently working on (non-Archimedean) valuations and absolute values. My text states that one example, where I have both a non-Archimedean valuation and a corresponding absolute value is $mathbbC((t))$ , i.e. the field of formal power series with coefficients in $mathbbC$, defined as
$$mathbbC((t))= sum_k=m^infty a_kt^k : m in mathbbZ, a_k in mathbbC.$$



I tried to find how a valuation and an absolute value on this field are defined, but I came up empty-handed.
It would be great if any of you could help me! (If it helps - they mentioned in the same context also $mathbbQ_p$ with the $p$-adic valuation/ absolute value and the completion $mathbbC_p$).







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    I'm currently working on (non-Archimedean) valuations and absolute values. My text states that one example, where I have both a non-Archimedean valuation and a corresponding absolute value is $mathbbC((t))$ , i.e. the field of formal power series with coefficients in $mathbbC$, defined as
    $$mathbbC((t))= sum_k=m^infty a_kt^k : m in mathbbZ, a_k in mathbbC.$$



    I tried to find how a valuation and an absolute value on this field are defined, but I came up empty-handed.
    It would be great if any of you could help me! (If it helps - they mentioned in the same context also $mathbbQ_p$ with the $p$-adic valuation/ absolute value and the completion $mathbbC_p$).







    share|cite|improve this question





















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      I'm currently working on (non-Archimedean) valuations and absolute values. My text states that one example, where I have both a non-Archimedean valuation and a corresponding absolute value is $mathbbC((t))$ , i.e. the field of formal power series with coefficients in $mathbbC$, defined as
      $$mathbbC((t))= sum_k=m^infty a_kt^k : m in mathbbZ, a_k in mathbbC.$$



      I tried to find how a valuation and an absolute value on this field are defined, but I came up empty-handed.
      It would be great if any of you could help me! (If it helps - they mentioned in the same context also $mathbbQ_p$ with the $p$-adic valuation/ absolute value and the completion $mathbbC_p$).







      share|cite|improve this question











      I'm currently working on (non-Archimedean) valuations and absolute values. My text states that one example, where I have both a non-Archimedean valuation and a corresponding absolute value is $mathbbC((t))$ , i.e. the field of formal power series with coefficients in $mathbbC$, defined as
      $$mathbbC((t))= sum_k=m^infty a_kt^k : m in mathbbZ, a_k in mathbbC.$$



      I tried to find how a valuation and an absolute value on this field are defined, but I came up empty-handed.
      It would be great if any of you could help me! (If it helps - they mentioned in the same context also $mathbbQ_p$ with the $p$-adic valuation/ absolute value and the completion $mathbbC_p$).









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      asked Jul 22 at 12:27









      SallyOwens

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          The valuation $v(f(t))$ is given by the number of times $t$ divides the power series $f(t)$. The norm is then defined accordingly, i.e. one may define it by setting for example $|f(t)| := e^-v(f(t))$. (More generally, this kind of construction whenever you take a Dedekind domain and consider some nonzero prime ideal of it. In this case the ring is $mathbbC[[t]]$ and the ideal is $(t)$. The case where the domain is $mathbbZ$ and the ideal is $(p)$ gives the usual case of $mathbbQ_p$).






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            1 Answer
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            1 Answer
            1






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            active

            oldest

            votes








            up vote
            2
            down vote



            accepted










            The valuation $v(f(t))$ is given by the number of times $t$ divides the power series $f(t)$. The norm is then defined accordingly, i.e. one may define it by setting for example $|f(t)| := e^-v(f(t))$. (More generally, this kind of construction whenever you take a Dedekind domain and consider some nonzero prime ideal of it. In this case the ring is $mathbbC[[t]]$ and the ideal is $(t)$. The case where the domain is $mathbbZ$ and the ideal is $(p)$ gives the usual case of $mathbbQ_p$).






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              up vote
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              accepted










              The valuation $v(f(t))$ is given by the number of times $t$ divides the power series $f(t)$. The norm is then defined accordingly, i.e. one may define it by setting for example $|f(t)| := e^-v(f(t))$. (More generally, this kind of construction whenever you take a Dedekind domain and consider some nonzero prime ideal of it. In this case the ring is $mathbbC[[t]]$ and the ideal is $(t)$. The case where the domain is $mathbbZ$ and the ideal is $(p)$ gives the usual case of $mathbbQ_p$).






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                up vote
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                accepted







                up vote
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                accepted






                The valuation $v(f(t))$ is given by the number of times $t$ divides the power series $f(t)$. The norm is then defined accordingly, i.e. one may define it by setting for example $|f(t)| := e^-v(f(t))$. (More generally, this kind of construction whenever you take a Dedekind domain and consider some nonzero prime ideal of it. In this case the ring is $mathbbC[[t]]$ and the ideal is $(t)$. The case where the domain is $mathbbZ$ and the ideal is $(p)$ gives the usual case of $mathbbQ_p$).






                share|cite|improve this answer













                The valuation $v(f(t))$ is given by the number of times $t$ divides the power series $f(t)$. The norm is then defined accordingly, i.e. one may define it by setting for example $|f(t)| := e^-v(f(t))$. (More generally, this kind of construction whenever you take a Dedekind domain and consider some nonzero prime ideal of it. In this case the ring is $mathbbC[[t]]$ and the ideal is $(t)$. The case where the domain is $mathbbZ$ and the ideal is $(p)$ gives the usual case of $mathbbQ_p$).







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                answered Jul 22 at 12:33









                Gal Porat

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