On elementary abelian 2-Sylow K₂ of rings of integers of certain quadratic number fields

P. E. Conner; J. Hurrelbrink

Acta Arithmetica (1995)

  • Volume: 73, Issue: 1, page 59-65
  • ISSN: 0065-1036

Abstract

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A large number of papers have contributed to determining the structure of the tame kernel K F of algebraic number fields F. Recently, for quadratic number fields F whose discriminants have at most three odd prime divisors, 4-rank formulas for K F have been made very explicit by Qin Hourong in terms of the indefinite quadratic form x² - 2y² (see [7], [8]). We have made a successful effort, for quadratic number fields F = ℚ (√(±p₁p₂)), to characterize in terms of positive definite binary quadratic forms, when the 2-Sylow subgroup of the tame kernel of F is elementary abelian. This makes determining exactly when the 4-rank of K F is zero, computationally even more accessible. For arbitrary algebraic number fields F with 4-rank of K F equal to zero, it has been pointed out that the Leopoldt conjecture for the prime 2 is valid for F, compare [6]. We consider this paper to be an addendum to the Acta Arithmetica publications [7], [8]. It grew out of our circulated 1989 notes [3]. Acknowledgements. We gratefully acknowledge fruitful long-term communications on this topic with Jerzy Browkin.

How to cite

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P. E. Conner, and J. Hurrelbrink. "On elementary abelian 2-Sylow K₂ of rings of integers of certain quadratic number fields." Acta Arithmetica 73.1 (1995): 59-65. <http://eudml.org/doc/206810>.

@article{P1995,
abstract = {A large number of papers have contributed to determining the structure of the tame kernel $K₂_F$ of algebraic number fields F. Recently, for quadratic number fields F whose discriminants have at most three odd prime divisors, 4-rank formulas for $K₂_F$ have been made very explicit by Qin Hourong in terms of the indefinite quadratic form x² - 2y² (see [7], [8]). We have made a successful effort, for quadratic number fields F = ℚ (√(±p₁p₂)), to characterize in terms of positive definite binary quadratic forms, when the 2-Sylow subgroup of the tame kernel of F is elementary abelian. This makes determining exactly when the 4-rank of $K₂_F$ is zero, computationally even more accessible. For arbitrary algebraic number fields F with 4-rank of $K₂_F$ equal to zero, it has been pointed out that the Leopoldt conjecture for the prime 2 is valid for F, compare [6]. We consider this paper to be an addendum to the Acta Arithmetica publications [7], [8]. It grew out of our circulated 1989 notes [3]. Acknowledgements. We gratefully acknowledge fruitful long-term communications on this topic with Jerzy Browkin.},
author = {P. E. Conner, J. Hurrelbrink},
journal = {Acta Arithmetica},
keywords = {quadratic number fields; positive definite binary quadratic forms; 2-Sylow subgroup; elementary abelian},
language = {eng},
number = {1},
pages = {59-65},
title = {On elementary abelian 2-Sylow K₂ of rings of integers of certain quadratic number fields},
url = {http://eudml.org/doc/206810},
volume = {73},
year = {1995},
}

TY - JOUR
AU - P. E. Conner
AU - J. Hurrelbrink
TI - On elementary abelian 2-Sylow K₂ of rings of integers of certain quadratic number fields
JO - Acta Arithmetica
PY - 1995
VL - 73
IS - 1
SP - 59
EP - 65
AB - A large number of papers have contributed to determining the structure of the tame kernel $K₂_F$ of algebraic number fields F. Recently, for quadratic number fields F whose discriminants have at most three odd prime divisors, 4-rank formulas for $K₂_F$ have been made very explicit by Qin Hourong in terms of the indefinite quadratic form x² - 2y² (see [7], [8]). We have made a successful effort, for quadratic number fields F = ℚ (√(±p₁p₂)), to characterize in terms of positive definite binary quadratic forms, when the 2-Sylow subgroup of the tame kernel of F is elementary abelian. This makes determining exactly when the 4-rank of $K₂_F$ is zero, computationally even more accessible. For arbitrary algebraic number fields F with 4-rank of $K₂_F$ equal to zero, it has been pointed out that the Leopoldt conjecture for the prime 2 is valid for F, compare [6]. We consider this paper to be an addendum to the Acta Arithmetica publications [7], [8]. It grew out of our circulated 1989 notes [3]. Acknowledgements. We gratefully acknowledge fruitful long-term communications on this topic with Jerzy Browkin.
LA - eng
KW - quadratic number fields; positive definite binary quadratic forms; 2-Sylow subgroup; elementary abelian
UR - http://eudml.org/doc/206810
ER -

References

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  1. [1] P. Barrucand and H. Cohn, Note on primes of type x² + 32y², class number and residuacity, J. Reine Angew. Math. 238 (1969), 67-70. Zbl0207.36202
  2. [2] P. E. Conner and J. Hurrelbrink, Class Number Parity, Ser. Pure Math. 8, World Sci., Singapore, 1988. 
  3. [3] P. E. Conner and J. Hurrelbrink, Examples of quadratic number fields with K₂𝓞 containing no element of order four, circulated notes, 1989. 
  4. [4] P. E. Conner and J. Hurrelbrink, The 4-rank of K₂𝓞, Canad. J. Math. 41 (1989), 932-960. Zbl0705.19006
  5. [5] J. Hurrelbrink, Circulant graphs and 4-ranks of ideal class groups, J. Math. 46 (1994), 169-183. Zbl0792.05133
  6. [6] M. Kolster, Remarks on étale K-theory and the Leopoldt conjecture, in: Séminaire de Théorie des Nombres, Paris, 1991-92, Progr. Math. 116, Birkhäuser, 1993, 37-62. 
  7. [7] H. Qin, The 2-Sylow subgroups of the tame kernel of imaginary quadratic fields, Acta Arith. 69 (1995), 153-169. Zbl0826.11055
  8. [8] H. Qin, The 4-rank of K O F for real quadratic fields, Acta Arith. 72 (1995), 323-333. 
  9. [9] B. A. Venkov, Elementary Number Theory, Wolters-Noordhoff, Groningen, 1970 

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