English

A homotopical Skolem--Noether theorem

Algebraic Geometry 2022-07-01 v3 Algebraic Topology Rings and Algebras

Abstract

The classical Skolem--Noether Theorem [Giraud, 71] shows us (1) how we can assign to an Azumaya algebra AA on a scheme XX a cohomological Brauer class in H2(X,Gm)H^2(X,\mathbf G_m) and (2) how Azumaya algebras correspond to twisted vector bundles. The Derived Skolem--Noether Theorem [Lieblich, 09] generalizes this result to weak algebras in the derived 1-category locally quasi-isomorphic to derived endomorphism algebras of perfect complexes. We show that in general for a co-family C\mathscr C^\otimes of presentable monoidal quasi-categories with descent over a quasi-category with a Grothendieck topology, there is a fibre sequence giving in particular the above correspondences. For a totally supported perfect complex EE over a quasi-compact and quasi-separated scheme XX, the long exact sequence on homotopy group sheaves splits giving equalities πi(AutPerfE,idE)=πi(AutAlgPerfREndE,idREndE)\pi_i(\mathop{\mathrm{Aut}}_{\mathop{\mathrm{Perf}}} E,\mathrm{id}_E)=\pi_i(\mathop{\mathrm{Aut}}_{\mathop{\mathrm{Alg}}\mathop{\mathrm{Perf}}}\mathop{\mathbf R\mathrm{End} E},\mathrm{id}_{\mathop{\mathbf R\mathrm{End} E}}) for i1i\ge1. Further applications include complexes in Derived Algebraic Geometry, module spectra in Spectral Algebraic Geometry and ind-coherent sheaves and crystals in Derived Algeraic Geometry in characteristic 0.

Keywords

Cite

@article{arxiv.2007.14327,
  title  = {A homotopical Skolem--Noether theorem},
  author = {Ajneet Dhillon and Pál Zsámboki},
  journal= {arXiv preprint arXiv:2007.14327},
  year   = {2022}
}

Comments

56 pages. Minor changes

R2 v1 2026-06-23T17:28:13.212Z