Vector Flow in Lie Group Theory
Relevant concepts: (exponential map, infinitesimal generator, one-parameter group)
Every left-invariant vector field on a Lie group is complete. The integral curve starting at the identity is a one-parameter subgroup of G. There are one-to-one correspondences
- {one-parameter subgroups of G} ⇔ {left-invariant vector fields on G} ⇔ g = TeG.
Let G be a Lie group and g its Lie algebra. The exponential map is a map exp : g → G given by exp(X) = γ(1) where γ is the integral curve starting at the identity in G generated by X.
- The exponential map is smooth.
- For a fixed X, the map t ↦ exp(tX) is the one-parameter subgroup of G generated by X.
- The exponential map restricts to a diffeomorphism from some neighborhood of 0 in g to a neighborhood of e in G.
- The image of the exponential map always lies in the connected component of the identity in G.
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