English

Higher Koszul brackets on the cotangent complex

Algebraic Geometry 2024-06-04 v2 Commutative Algebra Quantum Algebra Representation Theory Symplectic Geometry

Abstract

Let n1n\ge 1 and AA be a commutative algebra of the form k[x1,x2,,xn]/I\boldsymbol k[x_1,x_2,\dots, x_n]/I where k\boldsymbol k is a field of characteristic 00 and Ik[x1,x2,,xn]I\subseteq \boldsymbol k[x_1,x_2,\dots, x_n] is an ideal. Assume that there is a Poisson bracket {,}\{\:,\:\} on SS such that {I,S}I\{I,S\}\subseteq I and let us denote the induced bracket on AA by {,}\{\:,\:\} as well. It is well-known that [dxi,dxj]:=d{xi,xj}[\mathrm d x_i,\mathrm d x_j]:=\mathrm d\{x_i,x_j\} defines a Lie bracket on the AA-module ΩAk\Omega_{A|\boldsymbol k} of K\"ahler differentials making (A,ΩAk)(A,\Omega_{A|\boldsymbol k}) a Lie-Rinehart pair. Recall that AA is regular if and only if ΩAk\Omega_{A|\boldsymbol k} is projective as an AA-module. If AA is not regular, the cotangent complex LAk\mathbb L_{A|\boldsymbol k} may serve as a replacement for the AA-module ΩAk\Omega_{A|\boldsymbol k}. We prove that there is a structure of an LL_\infty-algebroid on LAk\mathbb L_{A|\boldsymbol k}, compatible with the Lie-Rinehart pair (A,ΩAk)(A,\Omega_{A|\boldsymbol k}). The LL_\infty-algebroid on LAk\mathbb L_{A|\boldsymbol k} actually comes from a PP_\infty-algebra structure on the resolvent of the morphism k[x1,x2,,xn]Ak[x_1,x_2,\dots, x_n]\to A. We identify examples when this LL_\infty-algebroid simplifies to a dg Lie algebroid. For aesthetic reasons we concentrate on cases when k[x1,x2,,xn] \boldsymbol k[x_1,x_2,\dots, x_n] carries a (possibly nonstandard) Z0\mathbb Z_{\ge 0}-grading and both II and {,}\{\:,\:\} are homogeneous.

Keywords

Cite

@article{arxiv.2107.04204,
  title  = {Higher Koszul brackets on the cotangent complex},
  author = {Hans-Christian Herbig and Daniel Herden and Christopher Seaton},
  journal= {arXiv preprint arXiv:2107.04204},
  year   = {2024}
}

Comments

32 pages, 2 tables. V2: We corrected an error in the bracket table of the invariants of the Kleinian singularity E_7 (which does not appear in the published version in IMRN, https://doi.org/10.1093/imrn/rnac170) that was identified by William Osnayder Clavijo Esquivel; we express our appreciation for identifying this error

R2 v1 2026-06-24T04:01:44.099Z