Determination of the isovector equation-of-state in heavy ion collisions

The isovector part of the equation-of-state, i.e. the density (and momentum and temperature) dependence of the symmetry energy is largely uncertain from different theoretical approaches, but is of importance in nuclear structure of exotic nuclei and in astrophysics. Here we review how information on the density dependence can be obtained from heavy ion collisions, both at Fermi energies for densities below and for relativistic energies above saturation. We discuss sensitive observables and compare to the present experimental situation.