• 제목/요약/키워드: Abelian function field

검색결과 6건 처리시간 0.018초

On the ring of integers of cyclotomic function fields

  • Bae, Sunghan;Hahn, Sang-Geun
    • 대한수학회보
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    • 제29권1호
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    • pp.153-163
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    • 1992
  • Carlitz module is used to study abelian extensions of K=$F_{q}$(T). In number theory every abelian etension of Q is contained in a cyclotomic field. Similarly every abelian extension of $F_{q}$(T) with some condition on .inf. is contained in a cyclotomic function field. Hence the study of cyclotomic function fields in analogy with cyclotomic fields is an important subject in number theory. Much are known in this direction such as ring of integers, class groups and units ([G], [G-R]). In this article we are concerned with the ring of integers in a cyclotomic function field. In [G], it is shown that the ring of integers is generated by a primitive root of the Carlitz module using the ramification theory and localization. Here we will give another proof, which is rather elementary and explicit, of this fact following the methods in [W].[W].

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CYCLOTOMIC UNITS AND DIVISIBILITY OF THE CLASS NUMBER OF FUNCTION FIELDS

  • Ahn, Jae-Hyun;Jung, Hwan-Yup
    • 대한수학회지
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    • 제39권5호
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    • pp.765-773
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    • 2002
  • Let $textsc{k}$$F_{q}$(T) be a rational function field. Let $\ell$ be a prime number with ($\ell$, q-1) = 1. Let K/$textsc{k}$ be an elmentary abelian $\ell$-extension which is contained in some cyclotomic function field. In this paper, we study the $\ell$-divisibility of ideal class number $h_{K}$ of K by using cyclotomic units.s.s.

ON RELATIVE-INVARIANT CIRCULAR UNITS IN FUNCTION FIELDS

  • JUNG, HWANYUP
    • 호남수학학술지
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    • 제27권3호
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    • pp.389-397
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    • 2005
  • Let K be an absolutely real abelian number field with $G=Gal(K/{\mathbb{Q}})$. Let E be a subfield of K and ${\Delta}=Gal(K/E)$. Let $C_K$ and $C_E$ be the group of circular units of K and E respectively. In [G], Greither has shown that if G is cyclic then $C_K^{\Delta}=C_E$. In this paper we show that the same result holds in function field case.

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THAINE'S THEOREM IN FUNCTION FIELD

  • Jung, Hwanyup
    • 충청수학회지
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    • 제22권1호
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    • pp.17-23
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    • 2009
  • Let F be a finite real abelian extension of a global function field k with G = Gal(F/k). Assume that F is an extension field of the Hilbert class field $K_e$ of k and is contained in a cyclotomic function field $K_n$. Let $\ell$ be any prime number not dividing $ph_k{\mid}G{\mid}$. In this paper, we show that if $\theta{\in}\mathbb{Z}[G]$ annihilates the Sylow $\ell$-subgroup of ${\mathcal{O}}^{\times}_F/{\mathcal{C}}_F$, then (q-1)$\theta$ annihilates the Sylow $\ell$-subgroup of ${\mathcal{Cl}}_F$.

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