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In this paper we study a spectrum $K(mathcal{V}_k)$ such that $pi_0 K(mathcal{V}_k)$ is the Grothendieck ring of varieties and such that the higher homotopy groups contain more geometric information about the geometry of varieties. We use the topology of this spectrum to analyze the structure of $K_0[mathcal{V}_k]$ and show that classes in the kernel of multiplication by $[mathbb{A}^1]$ can always be represented as $[X]-[Y]$ where $X$ and $Y$ are varieties such that $[X] eq [Y]$, $Xtimes mathbb{A}^1$ and $Ytimes mathbb{A}^1$ are not piecewise isomorphic, but $[Xtimes mathbb{A}^1] =[Ytimes mathbb{A}^1]$ in $K_0[mathcal{V}_k]$. Along the way we present new proofs of the result of Larsen--Lunts on the structure on $K_0[mathcal{V}_k]/([mathbb{A}^1])$.
We show that an old conjecture of A.A. Suslin characterizing the image of a Hurewicz map from Quillen K-theory in degree $n$ to Milnor K-theory in degree $n$ admits an interpretation in terms of unstable ${mathbb A}^1$-homotopy sheaves of the general
We define the Chow $t$-structure on the $infty$-category of motivic spectra $SH(k)$ over an arbitrary base field $k$. We identify the heart of this $t$-structure $SH(k)^{cheartsuit}$ when the exponential characteristic of $k$ is inverted. Restricting
We show that if X is a toric scheme over a regular ring containing a field then the direct limit of the K-groups of X taken over any infinite sequence of nontrivial dilations is homotopy invariant. This theorem was known in characteristic 0. The affi
We do three things in this paper: (1) study the analog of localization sequences (in the sense of algebraic $K$-theory of stable $infty$-categories) for additive $infty$-categories, (2) define the notion of nilpotent extensions for suitable $infty$-c
We establish a kind of degree zero Freudenthal Gm-suspension theorem in motivic homotopy theory. From this we deduce results about the conservativity of the P^1-stabilization functor. In order to establish these results, we show how to compute cert