Global dynamics of stationary solutions of the extended Fisher-Kolmogorov equation

Agraïments: J.L. is partially supported by ICREA Academia. M.M. is supported by CNPq-Brazil under the Project No. 305204/2009-2. P.R.S. is partially supported by CNPq and FAPESP. All the authors are supported by the Int. Coop. Proj. CAPES/MECD-TQED II and PHB-2009-0025.In this paper we study the fourth order differential equation d 4u /dt4 + q (d 2u /dt2 )+ u 3 − u = 0, which arises from the study of stationary solutions of the Extended Fisher-Kolmogorov equation. Denoting x = u, y = du/ dt , z = d 2u/ dt2 , v = d 3u/ dt3 this equation becomes equivalent to the polynomial system ˙x = y, y˙ = z, z˙ = v, v˙ = x − qz − x 3 with (x, y, z, v) ∈ R 4 and q ∈ R. As usual, the dot denotes derivative with respect to the time t. Since the system has a first integral we can reduce our analysis to a family of systems on R 3 . We provide the global phase portrait of these systems in the Poincar'e ball (i.e. in the compactification of R 3 with the sphere S 2 of the infinity)