Uniform estimates and limits for a two phase parabolic singular perturbation problem Luis CaffarelliC. LedermanN. Wolanski 35R3535K6080A25free boundary problemheat equationparabolic singular perturbationviscosity solutions Indiana University Mathematics Journal 1997 text pdf 10.1512/iumj.1997.46.1470 10.1512/iumj.1997.46.1470 en Indiana Univ. Math. J. 46 (1997) 453 - 490 state-of-the-art mathematics http://iumj.org/access/