This paper studies the role of dg-Lie algebroids in derived deformation theory. More precisely, we provide an equivalence between the homotopy theories of formal moduli problems and dg-Lie algebroids over a commutative dg-algebra of characteristic zero. At the level of linear objects, we show that the category of representations of a dg-Lie algebroid is an extension of the category of quasi-coherent sheaves on the corresponding formal moduli problem. We describe this extension geometrically in terms of pro-coherent sheaves.between pro-coherent sheaves on X and pro-coherent T A/X -representations.Outline. The paper is outlined as follows. In Section 2, we recall the basic homotopy theory of dg-Lie algebroids over a commutative dg-algebra A, in which the weak equivalences are the quasi-isomorphisms. In Section 3 we provide model categorical descriptions of the homotopy theories of pro-coherent sheaves and procoherent Lie algebroids over A. Theorem 1.3 and its analogue in the coherent case are proven in Section 6, based on results about Lie algebroid cohomology that are discussed in Section 4 and 5. Section 7 is devoted to a proof of Theorem 1.4. As an application, we also show how Theorem 1.4 can be used to provide a simple point-set model for the Lie algebroid classifying the deformations of a (connective) commutative algebra over A (Proposition 7.18). Finally, in Section 8 we prove the equivalence of procoherent sheaves on formal moduli problems and representations of their associated Lie algebroid.Conventions. Throughout, let Q ⊆ k be a fixed connective commutative dgalgebra of characteristic zero and let A be a connective cdga over k. All differentialgraded objects are homologically graded, so that connective objects are concentrated in non-negative degrees. Given a chain complex V , we denote its suspension and cone by V [1] and V [0, 1]. Acknowledgement. The author was supported by NWO.
Recollections on DG-Lie algebroidsIn this section we recall the homotopy theory of dg-Lie algebroids over a commutative dg-algebra, based on the discussion in [18].2.1. DG-Lie algebroids. Recall that the tangent module of a commutative dg-kalgebra A is the dg-A-module of k-linear derivations of A