No Arabic abstract
We show that the celebrated operad of pre-Lie algebras is very rigid: it has no non-obvious degrees of freedom from either of the three points of view: deformations of maps to and from the three graces of operad theory, homotopy automorphisms, and operadic twisting. Examining the latter, it is possible to answer two questions of Markl from 2005, including a Lie-theoretic version of the Deligne conjecture.
Let $g_1$ and $g_2$ be two dg Lie algebras, then it is well-known that the $L_infty$ morphisms from $g_1$ to $g_2$ are in 1-1 correspondence to the solutions of the Maurer-Cartan equation in some dg Lie algebra $Bbbk(g_1,g_2)$. Then the gauge action by exponents of the zero degree component $Bbbk(g_1,g_2)^0$ on $MCsubsetBbbk(g_1,g_2)^1$ gives an explicit homotopy relation between two $L_infty$ morphisms. We prove that the quotient category by this relation (that is, the category whose objects are $L_infty$ algebras and morphisms are $L_infty$ morphisms modulo the gauge relation) is well-defined, and is a localization of the category of dg Lie algebras and dg Lie maps by quasi-isomorphisms. As localization is unique up to an equivalence, it is equivalent to the Quillen-Hinich homotopical category of dg Lie algebras [Q1,2], [H1,2]. Moreover, we prove that the Quillens concept of a homotopy coincides with ours. The last result was conjectured by V.Dolgushev [D].
In this paper, we develop the deformation theory controlled by pre-Lie algebras; the main tool is a new integration theory for pre-Lie algebras. The main field of application lies in homotopy algebra structures over a Koszul operad; in this case, we provide a homotopical description of the associated Deligne groupoid. This permits us to give a conceptual proof, with complete formulae, of the Homotopy Transfer Theorem by means of gauge action. We provide a clear explanation of this latter ubiquitous result: there are two gauge elements whose action on the original structure restrict its inputs and respectively its output to the homotopy equivalent space. This implies that a homotopy algebra structure transfers uniformly to a trivial structure on its underlying homology if and only if it is gauge trivial; this is the ultimate generalization of the $dd^c$-lemma.
In this paper, we initiate the generalisation of the operadic calculus which governs the properties of homotopy algebras to a properadic calculus which governs the properties of homotopy gebras over a properad. In this first article of a series, we generalise the seminal notion of infini-morphisms and the ubiquitous homotopy transfer theorem. As an application, we recover the homotopy properties of involutive Lie bialgebras developed by Cieliebak--Fukaya--Latschev and we produce new explicit formulas.
In our recent papers [Sh1,2], we introduced a {it twisted tensor product} of dg categories, and provided, in terms of it, {it a contractible 2-operad $mathcal{O}$}, acting on the category of small dg categories, in which the natural transformations are derived. We made use of some homotopy theory developed in [To] to prove the contractibility of the 2-operad $mathcal{O}$. The contractibility is an important issue, in vein of the theory of Batanin [Ba1,2], according to which an action of a contractible $n$-operad on $C$ makes $C$ a weak $n$-category. In this short note, we provide a new elementary proof of the contractibility of the 2-operad $mathcal{O}$. The proof is based on a direct computation, and is independent from the homotopy theory of dg categories (in particular, it is independent from [To] and from Theorem 2.4 of [Sh1]).
In this paper, we study weakly unital dg categories as they were defined by Kontsevich and Soibelman [KS, Sect.4]. We construct a cofibrantly generated Quillen model structure on the category $mathrm{Cat}_{mathrm{dgwu}}(Bbbk)$ of small weakly unital dg categories over a field $Bbbk$. Our model structure can be thought of as an extension of the model structure on the category $mathrm{Cat}_{mathrm{dg}}(Bbbk)$ of (strictly unital) small dg categories over $Bbbk$, due to Tabuada [Tab]. More precisely, we show that the imbedding of $mathrm{Cat}_{mathrm{dg}}(Bbbk)$ to $mathrm{Cat}_{mathrm{dgwu}}(Bbbk)$ is a right adjoint of a Quillen pair of functors. We prove that this Quillen pair is, in turn, a Quillen equivalence. In course of the proof, we study a non-symmetric dg operad $mathcal{O}$, governing the weakly unital dg categories, which is encoded in the Kontsevich-Soibelman definition. We prove that this dg operad is quasi-isomorphic to the operad $mathrm{Assoc}_+$ of unital associative algebras.