N Soliton Solutions to The Bogoyavlenskii-Schiff Equation and A Quest   for The Soliton Solution in (3 + 1) Dimensions
  We study the integrable systems in higher dimensions which can be written not by the Hirota's bilinear form but by the trilinear form. We explicitly discuss about the Bogoyavlenskii-Schiff(BS) equation in (2 + 1) dimensions. Its analytical proof of multi soliton solution and a new feature are given. Being guided by the strong symmetry, we also propose a new equation in (3 + 1) dimensions. 
Yu. S.J(1), K. Toda(1),N. Sasa(2) and T. Fukuyama(1)((1)Ritsumeikan   Univ., (2)Japan Atomic Energy Research Institute)