Lie groups #
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A Lie group is a group that is also a smooth manifold, in which the group operations of
multiplication and inversion are smooth maps. Smoothness of the group multiplication means that
multiplication is a smooth mapping of the product manifold G
× G
into G
.
Note that, since a manifold here is not second-countable and Hausdorff a Lie group here is not guaranteed to be second-countable (even though it can be proved it is Hausdorff). Note also that Lie groups here are not necessarily finite dimensional.
Main definitions and statements #
lie_add_group I G
: a Lie additive group whereG
is a manifold on the model with cornersI
.lie_group I G
: a Lie multiplicative group whereG
is a manifold on the model with cornersI
.normed_space_lie_add_group
: a normed vector space over a nontrivially normed field is an additive Lie group.
Implementation notes #
A priori, a Lie group here is a manifold with corners.
The definition of Lie group cannot require I : model_with_corners 𝕜 E E
with the same space as the
model space and as the model vector space, as one might hope, beause in the product situation,
the model space is model_prod E E'
and the model vector space is E × E'
, which are not the same,
so the definition does not apply. Hence the definition should be more general, allowing
I : model_with_corners 𝕜 E H
.
- to_has_smooth_add : has_smooth_add I G
- smooth_neg : smooth I I (λ (a : G), -a)
A Lie (additive) group is a group and a smooth manifold at the same time in which the addition and negation operations are smooth.
Instances of this typeclass
- to_has_smooth_mul : has_smooth_mul I G
- smooth_inv : smooth I I (λ (a : G), a⁻¹)
A Lie group is a group and a smooth manifold at the same time in which the multiplication and inverse operations are smooth.
Instances of this typeclass
An additive Lie group is an additive topological group. This is not an instance for technical reasons, see note [Design choices about smooth algebraic structures].
A Lie group is a topological group. This is not an instance for technical reasons, see note [Design choices about smooth algebraic structures].