Stability of travelling multiple-front (multiple-back) wave solutions of the Fitzhugh-Nagumo equations

Consideration is devoted to travelling multiple-front (back) wave solutions of the FitzHugh-Nagumo equations of bistable type. In particular, stability of the 1-front (back) wave is proven. In the proof, the eigenvalue problem for the 1-front wave bifurcating from coexisting simple front and back waves is regarded as a bifurcation problem for projectivized eigenvalue equations, rather than treated as a linear eigenvalue problem for each fixed wave.