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:

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 p^N, with N equal to the number of components and p equal to the probability that a component is bug free.

One of Dijkstra's main questions was:

"Can the programmer arrange his activity in such a way that his growing product remains firmly in his intellectual grip, that he continues to understand what he is doing?" [EWD303]

To write structured programs, Dijkstra proposed five well-known techniques:

• sequencing
• operational abstraction
• representational abstraction
• configurational abstraction (cf. layered software)
• textual encapsulation (cf. modularity)

The latter two are discussed here.

Looking back at the late 1960s, Dijkstra mentioned that progress had been made in processor allocation, mainly due to the work of his students Bomhoff and Feijen. With respect to virtual storage implementations, however, Dijkstra humbly admitted that much had still to be done on this subject. Even though he had spent months trying to do so, he was stil not able to find the right abstractions. [EWD300]