On reduction maps for the étale and Quillen K-theory of curves and applications

Author(s):  
Stefan Barańczuk ◽  
Krzysztof Górnisiewicz

AbstractIn this paper we consider reduction of nontorsion elements in the étale and Quillen K-theory of a curve X over a number field. As an application we solve two problems: detecting linear dependence and the support problem.

2017 ◽  
Vol 163 (3) ◽  
pp. 533-546 ◽  
Author(s):  
JOHANNES SCHLEISCHITZ

AbstractIn a paper from 2010, Budarina, Dickinson and Levesley studied the rational approximation properties of curves parametrised by polynomials with integral coefficients in Euclidean space of arbitrary dimension. Assuming the dimension is at least three and excluding the case of linear dependence of the polynomials together with P(X) ≡ 1 over the rational number field, we establish proper generalisations of their main result.


2018 ◽  
Vol 2020 (6) ◽  
pp. 1748-1793 ◽  
Author(s):  
Oliver Braunling

Abstract We generalize a recent result of Clausen; for a number field with integers $\mathcal{O}$, we compute the K-theory of locally compact $\mathcal{O}$-modules. For the rational integers this recovers Clausen’s result as a special case. Our method of proof is quite different; instead of a homotopy coherent cone construction in $\infty$-categories, we rely on calculus of fraction type results in the style of Schlichting. This produces concrete exact category models for certain quotients, a fact that might be of independent interest. As in Clausen’s work, our computation works for all localizing invariants, not just K-theory.


Author(s):  
Georg Tamme

AbstractIn this paper we prove the p-adic analogue of a result of Hamida [11], namely that the p-adic Borel regulator introduced by Huber and Kings for the K-theory of a p-adic number field equals Karoubi's p-adic regulator up to an explicit rational factor.


Author(s):  
Grzegorz Banaszak ◽  
Piotr Krasoń

AbstractLetXbe a smooth, proper and geometrically irreducible curveXdefined over a number fieldFand letχbe a regular and proper model ofXoverOF,Sl. In this paper we address the problem of detecting the linear dependence over ℤlof elements in the étaleK-theory ofχ. To be more specific, letP∊Ket2n(χ)and let ⋀̂ ⊂Ket2n(χ)be a ℤl-submodule. Letrυ:Ket2n(χ)→Ket2n(χυ)be the reduction map for υ ∉Sl. We prove, under some conditions onX, that ifrυ($\(P)_circumflex\$) ∈rυ(⋀̂) for almost all υ of$\mathematical script capital(O) F,Sl\$then$\(P)_circumflex\$∈ ⋀̂ +Ket2n(χ)tor.


1999 ◽  
Vol 1999 (507) ◽  
pp. 81-91
Author(s):  
Kevin P Knudson

Abstract Let A be the coordinate ring of an affine elliptic curve (over an infinite field k) of the form X – {p}, where X is projective and p is a closed point on X. Denote by F the function field of X. We show that the image of H.(GL2 (A), ℤ) in H.(GL2 (F), ℤ) coincides with the image of H.(GL2 (k), ℤ). As a consequence, we obtain numerous results about the K-theory of A and X. For example, if k is a number field, we show that r2 (K2 (A) ⊗ ℚ) = 0, where rm denotes the mth level of the rank filtration.


Author(s):  
A. J. Berrick ◽  
M. Karoubi ◽  
P. A. Østvær

AbstractAs an application of our papers in hermitian K-theory, in favourable cases we prove the periodicity of hermitian K-groups with a shorter period than previously obtained. We also compute the homology and cohomology with field coeffcients of infinite orthogonal and symplectic groups of specific rings of integers in a number field.


Author(s):  
M. Rørdam ◽  
F. Larsen ◽  
N. Laustsen
Keyword(s):  

1982 ◽  
Vol 2 (4) ◽  
pp. 375-388
Author(s):  
Jiwu Wang ◽  
Tai Kang
Keyword(s):  

1973 ◽  
Vol 6 (1) ◽  
pp. 85-94 ◽  
Author(s):  
Pramod K. Sharma ◽  
Jan R. Strooker
Keyword(s):  

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