The Riemann problem for Kerr equations and non-uniqueness of selfsimilar entropy solutions

We solve the Riemann problem for a nonlinear full wave Maxwell system arising in nonlinear optics. This system is hyperbolic, some eigenvalues have non-constant multiplicity and are neither genuinely nonlinear, nor linearly degenerate. In a particular 2x2 reduced case, we are able to exhibit two distinct selfsimilar entropy solutions. We compute the amounts of entropy dissipation and compare them