On the history of Lie brackets, crossed modules, and Lie-Rinehart algebras
On the history of Lie brackets, crossed modules, and Lie-Rinehart algebras
<p style='text-indent:20px;'>This is an overview of ideas related to brackets in early homotopy theory, crossed modules, the obstruction 3-cocycle for the nonabelian extension problem, the Teichmüller cocycle, Lie-Rinehart algebras, Lie algebroids, and differential algebra.</p>