Cancellation theorem for framed motives of algebraic varieties

TL;DR

This paper proves a cancellation theorem for framed motives of algebraic varieties, extending Voevodsky's work and crucial for computing fibrant resolutions in motivic homotopy theory.

Contribution

It establishes a cancellation theorem for framed motives, linking it to linear framed motives, and advances the understanding of motivic spectra of algebraic varieties.

Findings

Proves the cancellation theorem for framed motives.

Reduces the theorem to a quasi-isomorphism for linear framed motives.

Provides tools for computing fibrant resolutions of suspension spectra.

Abstract

The machinery of framed (pre)sheaves was developed by Voevodsky [V1]. Based on the theory, framed motives of algebraic varieties are introduced and studied in [GP1]. An analog of Voevodsky's Cancellation Theorem [V1] is proved in this paper for framed motives stating that a natural map of framed $S^1$-spectra $$M_{fr}(X)(n)\to\underline{\textrm{Hom}}(\mathbb G,M_{fr}(X)(n+1)),\quad n\geq 0,$$ is a schemewise stable equivalence, where $M_{fr}(X)(n)$ is the $n$th twisted framed motive of $X$. This result is also necessary for the proof of the main theorem of [GP1] computing fibrant resolutions of suspension $\mathbb P^1$-spectra $\Sigma^\infty_{\mathbb P^1}X_+$ with $X$ a smooth algebraic variety. The Cancellation Theorem for framed motives is reduced to the Cancellation Theorem for linear framed motives stating that the natural map of complexes of abelian groups \[ \mathbb ZF(\Delta^\bullet \times X,Y) \to \mathbb ZF((\Delta^\bullet \times X)\wedge (\mathbb G_m,1),Y\wedge (\mathbb G_m,1)),\quad X,Y\in Sm/k, \] is a quasi-isomorphism, where $\mathbb ZF(X,Y)$ is the group of stable linear framed correspondences in the sense of [GP1].