Questions tagged [algebraic-k-theory]
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Algebraic K-theory and Witt groups
Let $S$ be a ring with involution (with 2 invertible). Suppose that the non connective algebraic K-theory $K(S)$ is 0 (i.e. $K_{n}(S)=0$, for all $n$).
Can we say something about the (higher) Witt ...
- 1,105
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Explicit description of transfer for $K_1$
Let $R$ be a commutative regular ring and let $s \in R$ be an element such that $R / s$ is also regular. Then we have a long exact localization sequence
$$
\ldots \rightarrow K_i(R/s) \rightarrow K_i(...
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The $K_1$-group of integer valued polynomials
Let $R=$ Int$(\mathbb{Z}) = \{f \in \mathbb{Q}[x]| f(\mathbb{Z}) \subset \mathbb{Z}\}$. I am interested to find $K_1(R)$. I list my trials below:
Let us construct a Milnor square $$\matrix{R&\...
- 141
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Abelianization of $\mathrm{GL}_n(\mathbb{Z})$
$\DeclareMathOperator\GL{GL}\DeclareMathOperator\SL{SL}$What is the abelianization of $\GL_n(\mathbb{Z})$? I know the abelianzation of $\GL_n(\mathbb{F})$ where $\mathbb{F}$ is a field and the ...
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Surjection onto $H_{2}(\mathrm{PGL}(2,\mathbb{C}),\mathbb{Z})$
Let $G \leq \mathrm{PGL}(2,\mathbb{C})$ be the subgroup of upper-triangular matrices. I am interested in the natural morphism on the Schur multiplier (i.e. group homology as discrete groups)
$H_{2}(G,...
- 285
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91
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Higher chow groups of affine toric varieties
Let $X$ be an affine toric variety defined over an algebraically closed field $k$ of characteristic zero.
I am trying to use Bloch’s Riemann-Roch Theorem for quasi-projective algebraic schemes in his ...
- 569
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Ring with vanishing $K_0$
Suppose we have a ring $R$ such that the Grothendieck group $K_{0}(R)=0$.
Question 1: Does it follow that there exists two positive natural numbers $n\neq m$ such that
$R^{m}$ is isomorphic to $ R^{n}$...
- 1,105
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Group completion of a monoid (braid groups)
Let $B_n$ be the braid group on $n$ strands, $B_{\infty}$ the direct limit of braid groups.
For a discrete group $G$, we let $BG$ to be the classifying space of $G$.
After reading this question, I was ...
- 110
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Homotopy coherence datum for composition of Becker-Gottlieb transfers
I have a question about certain detail in following answer by Denis Nardin adressing the concept of presheaves with transfer (mostly known in constructions in motivic homotopy theory) from viewpoint ...
- 5,780
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Vanishing differential of Brown-Gersten-Quillen spectral sequence
Let $k$ be an algebraically closed field of characteristic zero and $X$ be an affine, simplicial toric 3-fold over the field $k$. I am trying to use the Brown-Gersten-Quillen spectral sequence to ...
- 569
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Stable homology of general linear groups
For what class of rings $R$, is the stable homology (with various choices of coefficients) of $GL_n(R)$ known? Borel computed it rationally for number rings, Quillen computed it for finite fields. Are ...
- 965
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Grothendieck group and an almost localization
Let $T$ be a small triangulated category and let $S\subset T$ be a full triangulated subcategory. We denote this embedding by $I: S\rightarrow T$.
Let $F: T\rightarrow S$ be a triangulated functor ...
- 1,105
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The action of the Grothendieck group on higher K-theory groups
Let $(C,\otimes)$ be a monoidal (non symmetric) Waldhausen category. In particular, under these conditions,
$K_{0}(C)$ is a ring and $K_{i}(C)$ are $K_{0}(C)$-bimodule for any $i\in \mathbb{Z}$.
...
- 1,105
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Example of triangulated category with vanishing $K_0$
Let $R$ be a ring, let $\operatorname{Perf}(R)$ the category of perfect modules over $R$. Suppose we have $E$ an perfect $R$-module (concentrated in degree $0$) such that its class $[E]\in K_0(R)$ is ...
- 1,105
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$K_0$ of arithmetic surfaces
In his paper "Algebraic K-Theory and classfield theory of arithmetic surfaces", Annals of Mathematics 114 (1981), Spencer Bloch proved the following result: if $A$ is a finitely generated ...