We discuss the procedure for the exact solution of the Riemann problem in
special relativistic magnetohydrodynamics (MHD). We consider both initial
states leading to a set of only three waves analogous to the ones in
relativistic hydrodynamics, as well as generic initial states leading to the
full set of seven MHD waves. Because of its generality, the solution presented
here could serve as an important test for those numerical codes solving the MHD
equations in relativistic regimes.Comment: 36 pages, 13 figures. Minor changes to match published versio
