“…Some fine commutator estimates are needed, and the liminf is obtained since we need a particular modification of the argument in [104] that allows us to control the energy norm as time tends to infinity. More applications: The method of proof above is quite general and it can be applied to several other dispersive models of importance: BBM equations (Kwak-M. [70]), abcd type models [68,69] (small data case only, large data seems quite complicated), Camassa-Holm type equations (Alejo-Cortez-Kwak-M. [3]), KdV on the half line [12], the quite involved Zakharov-Rubenchik / Benney-Roskes system (María Martínez and José Palacios [91]), and the ILW model (M.-Ponce-Saut [106]).…”