Homotopy theory of post-Lie algebras
Andrey Lazarev, Yunhe Sheng, Rong Tang
TL;DR
The paper develops a comprehensive homotopy theory for $PostLie$ algebras via Koszul duality, identifying the controlling graded Lie algebra of coderivations on the cofree conilpotent cotrialgebra $\mathsf{ComTrias}^c(V)$ and showing that Maurer–Cartan elements correspond to $Post-Lie$ structures on a shifted space. It defines a deformation cohomology through MC twisting, proves that the second cohomology governs infinitesimal deformations, and introduces $PostLie_\infty$ algebras as MC elements that relate to open–closed homotopy Lie algebras and higher geometric structures. A homotopy Rota–Baxter theory on open–closed HTL algebras is developed, with certain operators inducing $PostLie_\infty$ structures, thereby connecting operator theory with higher homotopy post–Lie concepts. The framework yields a robust deformation theory, extensive examples from higher geometric settings, and a natural pathway to constructing homotopy post–Lie structures from $L_\infty$-actions and Rota–Baxter-type data, with potential implications for deformation theory and related geometry.
Abstract
In this paper, we study the homotopy theory of post-Lie algebras. Guided by Koszul duality theory, we consider the graded Lie algebra of coderivations of the cofree conilpotent graded cocommutative cotrialgebra generated by $V$. We show that in the case of $V$ being a shift of an ungraded vector space $W$, Maurer-Cartan elements of this graded Lie algebra are exactly post-Lie algebra structures on $W$. The cohomology of a post-Lie algebra is then defined using Maurer-Cartan twisting. The second cohomology group of a post-Lie algebra has a familiar interpretation as equivalence classes of infinitesimal deformations. Next we define a post-Lie$_\infty$ algebra structure on a graded vector space to be a Maurer-Cartan element of the aforementioned graded Lie algebra. Post-Lie$_\infty$ algebras admit a useful characterization in terms of $L_\infty$-actions (or open-closed homotopy Lie algebras). Finally, we introduce the notion of homotopy Rota-Baxter operators on open-closed homotopy Lie algebras and show that certain homotopy Rota-Baxter operators induce post-Lie$_\infty$ algebras.
