Stefan problems, Nonlinear initial, boundary and initial-boundary value problems for linear parabolic equations, regularity, growth condition, existence, uniqueness, Existence of generalized solutions of PDE, Variational inequalities, Article, Regularity of generalized solutions of PDE, 510.mathematics, initial boundary value problem, Nonlinear boundary value problems for linear elliptic equations, Free boundary problems for PDEs, monotone continuous subgradient, elliptic parabolic differential equations