Reduced phase spaces (p, φ) of the harmonics θ_1 : 1, θ_2 : 1, and θ_3 : 2 along the Lie-transformed nominal solution as deduced from the Lie-transformed Hamiltonian . The phase spaces correspond to the t₀ times indicated in the upper-right boxes. The black dots reproduce the level curves of the reduced Hamiltonian, and the orange dots represent its fixed points. The separatrices are shown by red dots, and the level curve corresponding to the resonant variables at time t₀ is shown in blue. The right-hand-side axes report the projection of the mean frequencies along the normal k to the resonance plane.