Richness or Semi-Hamiltonicity of quasi-linear systems which are not in evolution form

Abstract

The aim of this paper is to consider quasi-linear systems which are not in the form of evolution equations. We propose new condition of Richness or Semi-Hamiltonicity for such a system and prove that the blow up analysis along characteristic curves can be performed for it in an analogous manner. This opens a possibility to use this ansatz also for geometric problems. We apply the results to the problem of Polynomial integral for geodesic flows on the 2-torus.