Darboux covariant equations of von Neumann type and their generalizations

Abstract

Lax pairs with operator valued coefficients, which are explicitly connected by means of an additional condition, are considered. This condition is proved to be covariant with respect to the Darboux transformation of a general form. Nonlinear equations arising from the compatibility condition of the Lax pairs in the matrix case include, in particular, Nahm equations, and Volterra, Bogoyavlenskii and Toda lattices. The examples of other one-, two- and multi-field lattice equations are also presented. © 2003 American Institute of Physics.