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20132021
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math.AP2021

Bifurcations from degenerate orbits of solutions of nonlinear elliptic systems

Anna Gołębiewska, Joanna Kluczenko, Piotr Stefaniak

The aim of this paper is to study global bifurcations of non-constant solutions of some nonlinear elliptic systems, namely the system on a sphere and the Neumann problem on a ball.…

math.AP2020

Structure of sets of solutions of parametrised semi-linear elliptic systems on spheres

Anna Gołębiewska, Piotr Stefaniak

In this paper we study a parametrised non-cooperative symmetric semi-linear elliptic system on a sphere. Assuming that there exist critical orbits of the potential, we study the st…

math.AP2019

Connected sets of solutions of symmetric elliptic systems

Anna Gołębiewska, Sławomir Rybicki, Piotr Stefaniak

The purpose of this paper is twofold. First we study bifurcations of connected sets of critical orbits of some invariant functional from a given family of critical orbits. We use t…

math.AP2018

Global bifurcation index of critical orbit of strongly indefinite functional

Anna Gołębiewska, Piotr Stefaniak

In this paper we study an index of a critical orbit, defined in terms of the degree for invariant strongly indefinite functionals. We establish a relationship of this index with th…

math.AP2017

Bifurcations from the orbit of solutions of the Neumann problem

Anna Gołębiewska, Joanna Kluczenko, Piotr Stefaniak

The purpose of this paper is to study weak solutions of a nonlinear Neumann problem considered on a ball. Assuming that the potential is invariant, we consider an orbit of critical…

math.AP2017

Rabinowitz alternative for non-cooperative elliptic systems on geodesic balls

Sławomir Rybicki, Naoki Shioji, Piotr Stefaniak

The purpose of this paper is to study properties of continua (closed connected sets) of nontrivial solutions of non-cooperative elliptic systems considered on geodesic balls in $S^…