On regularity of a boundary point for porous medium equation (Q2734665)

The sufficient condition of the regularity of a boundary point \((x_0,t_0)\in \partial\Omega\times (0,T)\) for non-negative solution of a parabolic equation NEWLINE\[NEWLINEu_t- \sum_{i,j=1}^N \frac{\partial} {\partial x_j} \Biggl( a_{ij}(x,t) u^{m-1} \frac{\partial u}{\partial x_i} \Biggr)= 0,\quad m>1NEWLINE\]NEWLINE in the tube domain \(\Omega\times (0,T)\) is established. For quasilinear parabolic equation under the linear growth of coefficients the same regularity results have been obtained by W. P. Ziemer and N. Eklund.