English

$\mathcal D$-$\Omega$ duality on the contra side

Algebraic Geometry 2025-09-30 v12 Category Theory Rings and Algebras

Abstract

Given a smooth morphism of schemes XTX\rightarrow T, denote by DX/Tcr\mathcal D_{X/T}^{\mathsf{cr}} the sheaf of rings of fiberwise crystalline differential operators on XX relative to TT and by ΩX/T\Omega^\bullet_{X/T} the de Rham sheaf of DG-algebras of relative differential forms on XX over TT. Assume that the scheme XX is quasi-compact and semi-separated. We construct a commutative square diagram of triangulated equivalences between four triangulated categories: the derived category of quasi-coherent sheaves of DX/Tcr\mathcal D_{X/T}^{\mathsf{cr}}-modules, the reduced coderived category of quasi-coherent DG-modules over ΩX/T\Omega_{X/T}^\bullet, the derived category of contraherent cosheaves of DX/Tcr\mathcal D_{X/T}^{\mathsf{cr}}-modules, and the reduced contraderived category of contraherent DG-modules over ΩX/T\Omega_{X/T}^\bullet. The equivalence involving the contraderived category was previously known for affine varieties only; we use contraherent cosheaves in order to obtain a nonaffine generalization of the "contra side" of the story. The exposition is written in the generality of finite locally free twisted Lie algebroids (g,g~)(\mathfrak g,\widetilde{\mathfrak g}) over quasi-compact semi-separated schemes XX, the quasi-coherent twisted universal enveloping quasi-algebras of (g,g~)(\mathfrak g,\widetilde{\mathfrak g}), and the Chevalley-Eilenberg quasi-coherent CDG-quasi-algebras of (g,g~)(\mathfrak g,\widetilde{\mathfrak g}). The equivalence between the derived categories of quasi-coherent and contraherent A\mathcal A-modules, called the "naive co-contra correspondence", is proved quite generally for any quasi-coherent quasi-algebra A\mathcal A over XX.

Keywords

Cite

@article{arxiv.2504.18460,
  title  = {$\mathcal D$-$\Omega$ duality on the contra side},
  author = {Leonid Positselski},
  journal= {arXiv preprint arXiv:2504.18460},
  year   = {2025}
}

Comments

LaTeX 2e with xy-pic and one mathb symbol; 355 pages, 136 commutative diagrams. This long preprint draws from three shorter preprints arXiv:2505.07739, arXiv:2507.15425, and arXiv:2509.07645. v.12: new Corollaries 11.32, 11.39 and Remarks 13.8, 13.17 inserted, Section 12.4 created with improvement in Corollary 12.7, new Sections 14.9 and 15 added -- this is intended as a largely complete version

R2 v1 2026-06-28T23:11:34.756Z