Multiplicity and ellipticity of closed characteristics on compact star-shaped hypersurfaces in ${\mathbf{R}}^{2n}$

Huagui Duan, Hui Liu

In this paper, we firstly generalize some theories developed by I. Ekeland and H. Hofer in [EkH] for closed characteristics on compact convex hypersurfaces in ${\mathbf{R}}^{2n}$ to sta…