+ (u m

+ u xxx (! ref) mixes nonlinear convection with linear dispersion. Its solutions include the famous solitary waves, which pass through one another as solitons with no lasting eect other than a phase shift. These solitary waves are localised in space in the sense that they decay exponentially. In the early 1990s Rosenau and Hyman, motivated by the formation of patterns in liquid drops (! ref), investigated generalisations of the KdV equation in which the dispersion too is nonlinear. For m> 0 and 1 < n 3, they dened the compacton equation K(m;n) by u