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arXiv · 2009.09124

Cdh Descent for Homotopy Hermitian $K$-Theory of Rings with Involution

Daniel Carmody
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Abstract

We provide a geometric model for the classifying space of automorphism groups of Hermitian vector bundles over a ring with involution $R$ such that $\frac{1}{2} \in R$; this generalizes a result of Schlichting-Tripathi \cite{SchTri}. We then prove a periodicity theorem for Hermitian $K$-theory and use it to construct an $E_\infty$ motivic ring spectrum $\mathbf{KR}^{\mathrm{alg}}$ representing homotopy Hermitian $K$-theory. From these results, we show that $\mathbf{KR}^{\mathrm{alg}}$ is stable under base change, and cdh descent for homotopy Hermitian $K$-theory of rings with involution is a formal consequence.

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Daniel Carmody. 2020-09-19. Cdh Descent for Homotopy Hermitian $K$-Theory of Rings with Involution. https://arxiv.org/abs/2009.09124

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