Three solutions with precise sign properties for Gierer-Meinhardt type system
Abdelkrim Moussaoui
TL;DR
This work analyzes a sign-coupled Gierer–Meinhardt elliptic system with Neumann boundary conditions on a bounded smooth domain. It proves the existence of three distinct solutions: two with opposite constant signs and a third nodal pair when $\beta_1=0$, using a blend of sub-supersolution constructions and Leray–Schauder topological degree, including a regularized problem $(\mathrm{P}^{\varepsilon})$ to manage singular terms. The approach first secures two constant-sign solutions within carefully constructed rectangles, then employs degree theory to locate a third, nodal solution via a limiting process $\varepsilon\to0$. The results illuminate the sign structure and multiplicity of GM-type systems under Neumann conditions and demonstrate how cooperative/competitive dynamics (via $\beta_1=0$) influence solution topology.
Abstract
We establish the existence of three solutions for sign-coupled Gierer-Meinhardt type system with Neumann boundary conditions. Two solutions are of opposite constant-sign while the third solution is nodal with synchronous sign components. The approach combines sub-supersolutions method and Leray-Schauder topological degree involving perturbation argument.
