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:
Wirth and Dijkstra were close colleagues, thoroughly studying each other's writings in 1971. But how close, exactly, were they? How did Wirth's views differ from those of Dijkstra? In my first attempt to address these matters, I shall discuss a letter Wirth sent to Dijkstra in March 1971.
Is it correct to say that Dijkstra reasoned linguistically during the late 1950s and early 1960s? A reviewer of the research paper `Dijkstra's Rallying Cry ...' expressed his reservations about this matter.
In the previous post, "The reliability problem in a nutshell", the pessimistic assumption was made that each program component could interact with any other component. This resulted in the exponential factor pN, with N equal to the number of components and p equal to the probability that a component is bug free.
Given a specific function, called lambo, how do you prove that it is equal to its own inverse? Dijkstra's answer: by massaging a program that computes lambo. That is, by gradually transforming an original program that computes lambo into a symmetric program that is rather useless to the programmer but useful to the mathematician!
Consider a large program consisting of N individual components that can freely interact with each other. Suppose each component has a probability p of being right. Then the probability P that the whole program is right satisfies the following inequality:
Dijkstra went on a trip to California, visiting universities and research centers. While doing so, he got annoyed by the many researchers who viewed the difficulties underlying multi-person software projects as "communication problems" and who, therefore, advocated new specification languages.
On the basis of an IFIP WG 2.3 meeting in Han-sur-Lesse (Belgium), Dijkstra expressed his misgivings about the overhead projector. He preferred the blackboard much more and the interaction it required between him and the audience. That is, he preferred to give "lectures", not "presentations". Instead of preparing everything in advance, he wanted room to improvise during his lectures.