Long-term evolution of the HD 147018 system when varying the mutual inclination, i_mut (x-axis) and the inclination of the orbital plane, i (y-axis), both expressed in degrees. Top panels: maximal eccentricity of the inner planet, as defined by Eq. (19), without (left) and with (right) relativistic corrections. Bottom panels: libration amplitude of the argument of the pericenter, ω₁ (in degrees), as defined by Eq. (20), without (left) and with (right) relativistic corrections.