The Two-Phase Parabolic Signorini Problem Mark AllenWenhui Shi Indiana University Mathematics Journal 2016 text pdf 10.1512/iumj.2016.65.5824 10.1512/iumj.2016.65.5824 en Indiana Univ. Math. J. 65 (2016) 727 - 741 state-of-the-art mathematics http://iumj.org/access/