F. Lambert et al., ON A DIRECT BILINEARIZATION METHOD - KAUP HIGHER-ORDER WATER-WAVE EQUATION AS A MODIFIED NONLOCAL BOUSSINESQ EQUATION, Journal of physics. A, mathematical and general, 27(15), 1994, pp. 5325-5334
A systematic procedure for the bilinearization of classes of soliton e
quations is developed with the help of a generalization of Bell's expo
nential polynomials. Application of this procedure to Kaup's higher-or
der wave equation discloses several links with other soliton systems.
In particular, it is found that the Kaup equation is the modified vers
ion of a sech square soliton system which constitutes an alternative t
o the good Boussinesq equation.