Global bifurcation of solutions to elliptic systems with system and domain symmetries
Piotr Stefaniak
TL;DR
We address global bifurcation of weak solutions for parameterized elliptic systems on symmetric domains, exploiting the degree for equivariant gradient maps to detect bifurcation from a constant branch without requiring nondegeneracy. The method reduces to spectral data through the set $\Lambda=\{\beta_k/\alpha_j\}$ and uses the Euler ring of a torus to compute a bifurcation index $\mathcal{BIF}_{\mathbb{T}}(\lambda_0)$, guaranteeing global bifurcation when it is nontrivial. Symmetry breaking occurs at every nonzero bifurcation level on compact symmetric spaces, and under additional structural assumptions the bifurcating continua are unbounded, extending previous results to multi-eigenspace settings. The results provide a unified, symmetry-aware framework for global bifurcation in elliptic systems with group actions, with explicit implications for symmetric-space geometries such as spheres.
Abstract
We study parameterized elliptic systems on symmetric domains with additional system symmetries. We prove the existence of continua of nontrivial solutions bifurcating from the constant branch determined by a critical point of the potential, without assuming nondegeneracy, via the degree for equivariant gradient maps. Our assumptions are formulated in terms of the right-hand side. When the domain is a compact symmetric space, the bifurcating solutions break symmetry at every nonzero level. Under additional assumptions on the right-hand side, the continua are unbounded.
