Using the right notation is key to proving theorems elegantly. To get this message across, Van Gasteren and Dijkstra explained why they were dissatisfied with the notation that Courant and Robbins had used in a particular proof concerning the prime decomposition of a natural number m. The notation under scrutiny was:
In the Spring of 1981, A.J.M. van Gasteren and E.W. Dijkstra wanted to understand "how to tame the complexity of artefacts such as proofs and programs". In hindsight it is no surprise that Dijkstra's rallying cry for generalization in programming of the early 1960s is reflected in his work of the early 1980s with regards to proving mathematical theorems. Some examples below will illustrate this, based on AvG5/EWD788.
On 19 May 1981, Dijkstra spent the day in Munich with Bauer, Broy and Partsch in order to select the participants for the NATO Summer School in Marktoberdorf [EWD790]. It is interesting to note how close Dijkstra and Bauer had become by 1981.
David N. Freeman, director of Computing Activities at the University of Pennsylvania, contacted Dijkstra in order to express his interest in taking a sabbatical leave at Eindhoven between September 1972 and September 1973. As future posts on this blog will show, he was not the only one to do so. In fact, several American researchers in computing wanted to visit the Netherlands and Eindhoven in particular. Presumably, this was due to Dijkstra's presence at the University of Eindhoven.
The Dijkstra family collected many things, including an advertisement in NATURE on 4 February 1961, which mentioned the ALGOL 60 Programming School to be held at Brighton Technical College on 5 and 6 April 1961.
Dijkstra wrote a report in Dutch about his trip to Warwick (England), which took place right before Easter, 1971. The purpose of his trip was to attend an IFIP Working Group 2.3 meeting at Warwick University. Some points in Dijkstra's trip report are of general interest: