activity
20242026
collaborators

5 papers

math.FA2026

On the Uniqueness of the -Equivariant Spectral Flow

Marek Izydorek, Joanna Janczewska, Maciej Starostka +1

The spectral flow is an integer-valued homotopy invariant for paths of selfadjoint Fredholm operators. Lesch as well as Pejsachowicz, Fitzpatrick and Ciriza independently showed th…

math.DS2026

An Index Theorem in Relative K-Theory for First-Order Systems

Robert Skiba, Daniel Strzelecki, Nils Waterstraat

Motivated by bifurcation of branches of homoclinic orbits of dynamical systems, we consider families of first-order equations on the real line and introduce a generalisation of pre…

math.DS2025

A Comparison Principle for Bifurcation of Periodic Solutions of Hamiltonian Systems

Helene Cyris, Joanna Janczewska, Nils Waterstraat

We obtain novel criteria for the existence of local bifurcation for periodic solutions of Hamiltonian systems by a comparison principle of the spectral flow. Our method allows to f…

math.DS2024

Local and Global Bifurcation for Periodic Solutions of Hamiltonian Systems via Comparison Theory for the Spectral Flow

Joanna Janczewska, Maciej Starostka, Nils Waterstraat

We obtain local and global bifurcation for periodic solutions of Hamiltonian systems by using a new way to apply a comparison principle of the spectral flow that was originally int…

math.AP2024

Bifurcation for a Class of Indefinite Elliptic Systems by Comparison Theory for the Spectral Flow via an Index Theorem

J. Janczewska, M. Möckel, N. Waterstraat

We consider families of strongly indefinite systems of elliptic PDE and investigate bifurcation from a trivial branch of solutions by using the spectral flow. The novelty in our ap…