Results of a long-term N-body simulation of the nominal solution for system HD 31527. Top rows: semimajor axis a₃ and eccentricity e₃ of the outer planet as a function of time for the first 10⁵ yr of the integration. Lower left-hand plot: shows in green the difference in longitude of pericenter ϖ₃ − ϖ₂, and the red curve presents the behavior of the resonant angle σ₂ = 3λ₂ − 16λ₃ + 13ϖ₃. Lower right-hand graph: maximum Lyapunov exponent for the system during the complete simulation.