The map from
is a differentiable group homomorphism.
We have
In particular,
The given map is a group homomorphism by Lemma 4.5 part 4.
By definition,
As this power series (and its termwise derivative) are uniformly convergent on any compact subset, we can compute its derivative by differentiating termwise, which gives
A one-parameter subgroup of
for all
The infinitesimal generator of a one-parameter subgroup
(non-examinable) For a one-parameter subgroup
Indeed, if
The RHS is differentiable with respect to
It is well-defined for
The following is a very important property of one-parameter subgroups: that they all come from the exponential map.
Let
Then
for all
From the definition of one-parameter subgroups, we have
Now consider the differential equation
We
know that both
The map