Integrating L-infinity algebras
Andre Henriques
TL;DR
The paper develops a comprehensive framework to integrate L_infty-algebras into Lie n-groups by constructing Kan simplicial manifolds ∫L from Chevalley–Eilenberg data, and it analyzes the resulting simplicial homotopy. It shows that ∫L is Kan and encodes higher homotopy via H_{n-1}(L), extends the construction to Banach-manifold settings to manage infinite-dimensional cases, and introduces Postnikov-type truncations that yield Lie n-groups under concrete discreteness criteria. The string Lie 2-algebra str(g) is treated in depth, producing a model whose truncation τ_≤2 ∫str has the homotopy type of B String, and giving explicit, bundle-theoretic descriptions of its simplices. Overall, the work provides a robust integration procedure for L_infty-algebras, connects to existing string-group models, and clarifies the hierarchy between Lie 2-groups and higher coherent structures.
Abstract
Given an n-term L-infinity algebra L, we construct a Kan simplicial manifold which we think of as the 'Lie n-group' integrating L. This extends work of Getzler math.AT/0404003 . In the case of an ordinary Lie algebra, our construction gives the simplicial classifying space of the corresponding simply connect Lie group. In the case of the string Lie 2-algebra of Baez and Crans, this recovers the model of the string group introduced in math.QA/0504123 .
