English

Non-equivalences of motivic codimension filtration quotients

Algebraic Geometry 2024-10-07 v1 K-Theory and Homology

Abstract

We prove that a motivic equivalence of objects of the form \begin{equation*} X/(X-x)\simeq X^\prime/(X^\prime-x^\prime) \end{equation*} in H(B)\mathbf{H}^\bullet(B) or DM(B)\mathbf{DM}(B) over a scheme BB, where xx and xx^\prime are closed points of smooth BB-schemes XX and XX^\prime, implies an isomorphism of residue fields, i.e. xx.x\cong x^\prime. For a given d0d\geq 0, X,XSmBX,X^\prime\in\mathrm{Sm}_B, dimBX=d=dimBX\operatorname{dim}_B X=d=\operatorname{dim}_B X^\prime, and closed points xx and xx^\prime that residue fields are simple extensions of the ones of BB, we show an isomorphism of groups HomDM(B)(X/(Xx),X/(Xx)))Cor(x,x),\mathrm{Hom}_{\mathbf{DM}(B)}(X/(X-x),X^\prime/(X^\prime-x^\prime)))\cong\mathrm{Cor}(x,x^\prime), and prove that it leads to an equivalence of subcategories. Additionally, using the result on perverse homotopy heart by F.~D\'eglise and N.~Feld and F.~Jin and the strict homotopy invariance theorem for presheaves with transfers over fields by the first author, we prove an equivalence of the Rost cycle modules category and the homotopy heart of DM(k)\mathbf{DM}(k) over a field kk with integral coefficients.

Keywords

Cite

@article{arxiv.2410.03636,
  title  = {Non-equivalences of motivic codimension filtration quotients},
  author = {A. E. Druzhinin and A. A. Urazbaev},
  journal= {arXiv preprint arXiv:2410.03636},
  year   = {2024}
}

Comments

Theorems A, B ware not presented before. Theorem C was once presented and already deleted in arxiv: 2311.16264 before it was included in this new preprint