On a class of inhomogeneous extensions for integrable evolution systems
arXiv:nlin/0310032
Abstract
In the present paper we prove the integrability (in the sense of existence of formal symmetry of infinite rank) for a class of block-triangular inhomogeneous extensions of (1+1)-dimensional integrable evolution systems. An important consequence of this result is the existence of formal symmetry of infinite rank for "almost integrable" systems, recently discovered by Sanders and van der Kamp.
7 pages, LaTeX 2e, no figures, talk at the 8th International Conference on Differential Geometry and its Applications