SOLUTIONS OF THE DAVEY-STEWARTSON-II EQUATION WITH ARBITRARY RATIONALLOCALIZATION AND NONTRIVIAL INTERACTION

We study a large class of solutions of the Davey-Stewartson II equatio n obtained with the use of a Wronskian scheme. Unlike the well-known l umps, these solutions have an arbitrary rational localization in the p lane and describe typical interactions consisting of head-on collision s with a pi/2 scattering angle. We also find the connection between th e Wronskian method and the inverse spectral transform formalism associ ated with the lumps. We finally show that these novel solutions can al so be obtained through the method of coalescence of poles.