Harnack Inequalities and Nonlinear Operators Proceedings of the INdAM conference to celebrate the 70th birthday of Emmanuele DiBenedetto - Vespri, Vincenzo 1959-; Gianazza, Ugo; Monticelli, Dario Daniele; Punzo, Fabio; Andreucci, Daniele (Springer INdAM Series, 2021)