“…Here we adopt Kato's notion of well-posedness, which consists of existence, uniqueness, persistence property (i.e., if the data u 0 ∈ X a function space, then the corresponding solution u(•) describes a continuous curve in X, u ∈ C([0, T ]; X), T > 0), and continuous dependence of the map data-solution. Regarding the IVP for (HBO), in [14] LWP was deduced for s > 5/3 when d = 2 and for s > (d + 1)/2 when d ≥ 3. In [21], LWP was improved to the range s > 3/2 in the case d = 2.…”