Edsger Dijkstra was perhaps the best known, and certainly the most discussed, computer scientist of the seventies and eighties. We both knew Dijkstra though each of us in different ways and we both were aware that his inuence on computer science was not limited to his pioneering software projects and research articles. He interacted with his colleagues by way of numerous discussions, extensive letter correspondence, and hundreds of so-called EWD reports that he used to send to a select group of researchers. His renowned Tuesday Afternoon Club seminars, first in Eindhoven and later in Austin, instilled in others his uniquely systematic way of approaching research problems and developing solutions. His courses at the University of Texas in Austin were unlike any other, both in the choice of topics and in the meticulous way they were delivered. We felt that these aspects of Edsger's influence on the field might become forgotten and next to impossible to reconstruct. In fact, some of his collaborators and PhD students had died and his peers are over eighty years old. Accordingly, we began the task of documenting his impact on the life and work of his students, colleagues, and scientific friends, and learning more about his interactions with them. Continua, con testimonianze (fra gli altri) di Hoare, Knuth e Wirth, su https://www.cs.utexas.edu/users/EWD/commemoration/EWD-commemoration-2021.pdf Giacomo