Lie Algebroids
Eckhard Meinrenken
TL;DR
Lie algebroids provide a unifying infinitesimal framework for geometric structures by pairing a vector bundle $A\to M$ with a bracket on sections and an anchor $\mathsf a:A\to TM$ that satisfies a Leibniz-type rule. The paper outlines the core definitions, morphisms, pullbacks, and constructions, then develops the orbit foliation and splitting theorem to describe local models. It then connects Lie algebroids to Lie groupoids via the Lie functor, detailing integrability obstructions through monodromy groups and the Crainic–Fernandes integrability theorem, and finally presents the Lie algebroid complex, its contravariant viewpoint, and the Van Est map, linking algebroid cohomology to groupoid cohomology. The outlook highlights numerous directions, including bialgebroids, Dirac structures, and applications in Poisson and differential geometry. Overall, the work provides a consolidated perspective on infinitesimal-global correspondences and foundational tools for studying Lie algebroids and their integrations.
Abstract
This is an overview article on Lie algebroids, and their role as the infinitesimal counterparts of Lie groupoids.
