“…Much of the interest in these equations is that, firstly, they are integrable systems having a Lax pair, bi-Hamiltonian structure, hierarchies of symmetries and conservation laws; secondly, the peakon solutions are orbitally stable [15,16,17], which implies the shape of the peakon is unchanged under small perturbations; thirdly, they possess N -peakon weak solutions given by a linear superposition of single peakons with time-dependent amplitudes and speeds; and fourthly, they exhibit wave breaking in which certain smooth initial data yields solutions whose gradient u x blows up in a finite time while u stays bounded [9,10,11,12,13,14]. Moreover, the CH and DP equations arise as models for water waves [19,20,21], and it is known that the travelling wave solutions of greatest height for the Euler equations governing water waves have a peak at their crest (see [22,23,24,25] All of these equations, and their various modified versions and nonlinear generalizations [26,27,28,29,30,31,32], belong to the general family of nonlinear dispersive wave equations m t + f (u, u x )m + (g(u, u x )m) x = 0, m = u − u xx (1) where f and g are arbitrary non-singular functions of u and u x . Remarkably, as shown in recent work [33], every equation in this family (1) possesses N -peakon weak solutions…”