3 citations · 9 across the 15 of their papers we have counts for
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Mean index for non-periodic orbits in Hamiltonian systems
Xijun Hu, Li Wu
In this paper, we define mean index for non-periodic orbits in Hamiltonian systems and study its properties. In general, the mean index is an interval in R which is uniformly conti…
Spectral flow, Brouwer degree and Hill's determinant formula
Alessandro Portaluri, Li Wu
In 2005 a new topological invariant defined in terms of the Brouwer degree of a determinant map, was introduced by Musso, Pejsachowicz and the first name author for counting the co…
Sturm theory with applications in geometry and classical mechanics
Vivina L. Barutello, Daniel Offin, Alessandro Portaluri +1
Classical Sturm non-oscillation and comparison theorems as well as the Sturm theorem on zeros for solutions of second order differential equations have a natural symplectic version…
Morse index theorem for heteroclinic, homoclinic and halfclinic orbits of Lagrangian systems
Xijun Hu, Alessandro Portaluri, Li Wu +1
The purpose of this paper is to prove a new, more general version of the Morse index theorem for heteroclinic, homoclinic, and half-clinic solutions in general Lagrangian systems.…