“…There is a long list of literature devoted to studying the smoothness of solutions to unweighted quasilinear elliptic and parabolic equations, see e.g. [2,14,17,18,[26][27][28][29][30][31][33][34][35][36]38,56,57,73] and the references therein. Besides its own mathematical interest, this nonlinear evolution model is also of great relevance to applications in nonlinear porous media flow, image processing and game theory etc, see e.g.…”