The dynamics of a degenerate reaction diffusion equation

We consider the initial-boundary value problem for a degenerate reaction diffusion equation consisting of the porous medium operator plus a nonlinear reaction term. The structure of the set of equilibria depends on the length of the spatial domain. There are two critical lengths $\scriptstyle 0L_1$. Using a topological argument we show existence of connecting orbits joining the unstable equilibrium with the two stable equilibria for $\scriptstyle L\in(L_0, L_1]$, when there are three equilibria. By showing that the principle of linearized stability can sometimes be applied with succes to degenerate parabolic equations, these connections are found to be unique for $\scriptstyle L_