Bäcklund transformations connecting different isospectral deformation equations

Abstract
We study singular spectral problems on Riemann surfaces and isospectral deformation equations connected with them. We show that for a given class of reductions all spectral problems on a given Riemann surface give rise to the same class of isospectral deformation equations. These isospectral deformation equations can be solved using the Riemann boundary value problem. All possess local conservation laws and Bäcklund transformations.