Schaeffer's regularity theorem for scalar conservation laws does not extend to systems Laura CaravennaLaura Spinolo Indiana University Mathematics Journal 2017 text pdf 10.1512/iumj.2017.66.6010 10.1512/iumj.2017.66.6010 en Indiana Univ. Math. J. 66 (2017) 101 - 160 state-of-the-art mathematics http://iumj.org/access/