22 citations · 65 across the 30 of their papers we have counts for
6 papers · 1 filter
A remark on singular sets of vector bundle morphisms
Maciej Starostka, Nils Waterstraat
If a characteristic class for two vector bundles over the same base space does not coincide, then the bundles are not isomorphic. We give under rather common assumptions a lower bo…
Yet another proof of the Morse index theorem
Alessandro Portaluri, Nils Waterstraat
We give a new analytical proof of the Morse index theorem for geodesics in Riemannian manifolds.
Bifurcation of critical points for continuous families of C^2 functionals of Fredholm type
Jacobo Pejsachowicz, Nils Waterstraat
Given a continuous family of C^2 functionals of Fredholm type, we show that the non-vanishing of the spectral flow for the family of Hessians along a known (trivial) branch of crit…
On bifurcation for semilinear elliptic Dirichlet problems on geodesic balls
Alessandro Portaluri, Nils Waterstraat
We study bifurcation from a branch of trivial solutions of semilinear elliptic Dirichlet boundary value problems on a geodesic ball, whose radius is used as the bifurcation paramet…
A family index theorem for periodic Hamiltonian systems and bifurcation
Nils Waterstraat
We prove an index theorem for families of linear periodic Hamiltonian systems, which is reminiscent of the Atiyah-Singer index theorem for selfadjoint elliptic operators. For the s…
On bifurcation for semilinear elliptic Dirichlet problems and the Morse-Smale index theorem
Alessandro Portaluri, Nils Waterstraat
We study bifurcation from a branch of trivial solutions of semilinear elliptic Dirichlet boundary value problems on star-shaped domains, where the bifurcation parameter is introduc…