Alberto Farina, Enrico Valdinoci 1D symmetry for solutions of semilinear and quasilinear elliptic equations (351K, pdf) ABSTRACT. Several new 1D results for solutions of possibly singular or degenerate elliptic equations, inspired by a conjecture of De Giorgi, are provided. In particular, 1D symmetry is proven under the assumption that either the profiles at infinity are 2D, or that one level set is a complete graph, or that the solution is minimal or, more generally, Q-minimal.