Multilinear Hirota operators and integrability
  We consider multilinear generalization of the Hirota derivative, which serves as a building block for integrable solitonic hierarchies. 2 special integrable mutlilinear equations are shown to be splittable into pairs of bilinear operators, parametrized by the additional variable. This fact is a signature of a higher (B)KP reductions. 
I.A.Il'in, D.S.Noshchenko, A.S.Perezhogin
nlin.SI