Lie groups, Affine Connections

In summary, the conversation discusses the existence and uniqueness of an affine connection on a Lie group, with the property that all left invariant vector fields have a zero connection. It is also mentioned that this connection is torsion free if and only if the Lie algebra is Abelian. The conversation also touches on potential approaches to proving these statements, such as defining the connection at the identity and using left translation.
  • #1
zhangzujin
9
0
Let G be a Lie group. Show that there exists a unique affine connection such that [tex]\nabla X=0[/tex] for all left invariant vector fields. Show that this connection is torsion free iff the Lie algebra is Abelian.
 
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  • #2
Homework?
 
  • #3
hamster143 said:
Homework?
Aha. Of course not. I'm just reading Riemannian Geometry by Petersen, interested in the exercises of that.

In fact, my major is PDEs.
 
  • #4
The second statement shouldn't be bad, if you define the torsion tensor in terms of the connection and the commutator (i.e. show that [X,Y] is identically zero if and only if the Lie algebra is Abelian - shouldn't be too hard :) ).

For the first part, why not define the connection to be zero at the identity, and then drag all your vectors back there by left translation?
 

Related to Lie groups, Affine Connections

1. What is a Lie group?

A Lie group is a type of mathematical group that is continuous and smooth. It is used to study symmetries and transformations in various areas of mathematics, such as geometry and physics.

2. How are Lie groups related to affine connections?

Lie groups are closely related to affine connections, as they are used to represent the symmetries and transformations of a space that is equipped with an affine connection. The structure of a Lie group allows for the study of the properties and behavior of an affine connection.

3. What is an affine connection?

An affine connection is a mathematical concept that describes how tangent spaces are connected on a smooth manifold. It is used to define parallel transport, which is a way of moving vectors along curves on a manifold while maintaining their direction.

4. How are Lie groups and affine connections used in physics?

Lie groups and affine connections are used in physics to study the symmetries and transformations present in physical systems. They are particularly useful in the study of general relativity, where they are used to describe the structure of spacetime.

5. Can affine connections be defined on any type of space?

Yes, affine connections can be defined on any type of space that is equipped with a smooth structure. This includes both finite-dimensional spaces, such as Euclidean spaces, and infinite-dimensional spaces, such as function spaces.

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