When we were asked to be editors of this 20th anniversary special issue, we wondered what subject could be capable of including the very numerous lines of research in current mathematics. After a long reflection, we agreed that the topic that could unify the many souls of mathematics was to discuss the perspectives of our discipline.
What will the mathematics of tomorrow look like? We had the courage to invite mathematicians who had the same idea of mathematics as us. They have gifted us seven papers of excellent and profound mathematics which we hope will be ground for reflection and further discussion about the future directions of developments in the field.
Editors-in-Chief: Salvatore Marano (Department of Mathematics and Computer Science, University of Catania, Italy)
Vincenzo Vespri (Department of Mathematics and Computer Science, University of Florence, Italy)