diary70s

Some former colleagues of Dijkstra have stressed in interviews with me that Dijkstra was not an engineer (in accordance with their definition of the term). By discussing Dijkstra's characteristic top-down design perspective in my previous post, I have already given one reason why Dijkstra was perceived as a non-engineer. Below I present another reason. While doing so we will again encounter the dichotomy between performance and generality, a dichotomy which Dijkstra seems to have stressed throughout his whole career.

The implementation is inadequate, not the abstraction!

In a previous post I scrutinized Moshe Y. Vardi's account of Church and Turing. During the past months I refined that post and added it to the first chapter of my recent book The Dawn of Software Engineering: from Turing to Dijkstra. I now present a summary of my book and briefly explain how Turing's work influenced Dijkstra's thinking. The book has just appeared in print.

Summary

In the July 2011 issue of the Communications of the ACM you will find on page 5 a section entitled "Solving the Unsolvable", written by the editor in chief, Moshe Y. Vardi. In his words:

Roughly 80 participants from 15 countries participated in the 1971 summer school in Marktoberdorf. According to Dijkstra, some participants were very theoretically inclined, others more practically minded. Viewed from the present day, the following list of speakers at that summer school is impressive. Dijkstra attributed a theme to each speaker, with the exception of Perlis and Dahl:

The T.H.E. multiprogramming system — as designed and implemented by Dijkstra, Bron, Habermann, Hendriks, Ligtmans, and Voorhoeve — was studied by Mike McKeag during his visit to Eindhoven some time during the first half of 1971. Subsequently, McKeag went back to his university in Belfast (in Hoare's research group) where he wrote a report of the T.H.E. system. That report was sent to Dijkstra on 22 July 1971 with a cover letter stating:

Dear Professor Dijkstra,

Dijkstra visited the USA several times before moving to Texas in 1984. In the summer of 1971, he went on a trip to the USA and Canada. It wasn't his first trip to North America, but it was the first time his wife Ria accompanied him. The corresponding trip report was written by Dijkstra on June 23rd, 1971 in EWD312.

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.

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.