“…As we will show later, the role played by the Ablowitz-Segur solution and Airy function in the mKdV equation will be replaced by their higher-order generalizations. In the literatures, we note that the Painlevé transcendents and their higher-order analogues are crucial in asymptotic analysis of many integrable nonlinear differential equations, as can be seen from their appearances in the focusing nonlinear Schrödinger equation [4,5], in critical asymptotics for Hamiltonian perturbations of hyperbolic and elliptic systems [10], in the Camassa-Holm equation [7], in the Sasa-Satsuma equation [24], in an extended mKdV equation [30,31] and in the sine-Gordon equation [32]. The higher order asymptotics in similarity region for other integrable equations can be found in [26,37].…”