Differential graded algebras with divided powers and homotopy Lie algebras

Abstract

Given a commutative algebra $A$ and a quotient $A$-algebra $A/I$, we construct a resolution of $A/I$ as an $A$-module such that it is also a differential graded (dg) algebra with divided powers (PD). This construction makes use of symmetric tensors in the symmetric tensor category of dg $A$-modules and does not require a Noetherian assumption on $A$. Moreover, the resolution has many lifting properties which we leverage to study the homotopy Lie algebra associated to the pair $(A,A/I)$, which is defined as the image in the Yoneda algebra ${\mathrm{Ext}}_A^{\ast }(A/I,A/I)$ of the cohomology of the PD derivations of this PD dg algebra. Finally we investigate the complete intersection case in more details as well as connect it to the finite generation of the Yoneda algebra.

53 pages. Sections 3 and 4 have been improved upon and results have been added. The definition of the homotopy Lie algebra was slightly modified. References have been added