Аннотация:We consider singularly perturbed reaction–diffusion equations with singularly perturbed
Neumann boundary conditions. We establish the existence of a time-periodic solution u(x, t, ε)
with boundary layers and derive conditions for their asymptotic stability. The boundary layer
part of u(x, t, ε) is of order one, which distinguishes our case from the case of regularly perturbed
Neumann boundary conditions, where the boundary layer is of order ε. Another peculiarity of
our problem is that — in contrast to the case of Dirichlet boundary conditions — it may have
several asymptotically stable time-periodic solutions, where these solutions differ only in the
description of the boundary layers. Our approach is based on the construction of sufficiently
precise lower and upper solutions.