Smooth action of a Lie group on a manifold
A smooth map defining a group action of a Lie group on a smooth manifold.
Smooth action of a Lie group on a manifold
Let Lie group and smooth manifold be given.
A smooth left action of on is a smooth map
such that, writing , the following hold for all and :
- (Identity) .
- (Compatibility) .
For each , the map , , is a diffeomorphism with inverse .
A smooth right action is defined similarly, using a smooth map , , with and .
Examples
- Left translation on the group. acts on itself by .
- Rotations of the plane. acts on by matrix multiplication.
- Change of frame. The general linear group acts on the frame bundle of a manifold by post-composition of frames (a standard example of a right action in principal bundle theory).