Some new results on the Błaszak-Marciniak 3-field and 4-field lattices

By using the bilinear form of the 3-field Błaszak-Marciniak lattice and its corresponding Bäcklund transformation, a series of rational solutions are obtained. Starting from the bilinear form for the 4-field Błaszak-Marciniak lattice, a new lattice is found which has soliton solutions.