View source for Birkhoff theorem

This may refer to:

* The [[Birkhoff ergodic theorem]];
* The [[Birkhoff–Witt theorem]] or Poincaré–Birkhoff–Witt theorem on the representability of Lie algebras in associative algebras;
* The characterisation of a [[Algebraic systems, variety of|variety of algebraic systems]] as being closed with respect to subsystems, homomorphic images and Cartesian products.