Is there some reference containing an ellaboration of Morse Theory for proper actions of Lie groups?
1 Answer
$\begingroup$
$\endgroup$
Have a look at
N. Hingston, Equivariant Morse theory and closed geodesics, J. Differential Geom. Volume 19, Number 1 (1984), 1-276.
in particular Section 2. Most statements from the equivariant Morse theory for compact group actions go over unchanged, thanks to the existence of slices for proper actions; see
R. Palais, On the existence of slices for actions of noncompact Lie groups, Ann. of Math. 73 (1961)295-323.