Extrait de Oral History of Sir Antony Hoare
CHM Ref: X3698.2007 © 2006 Computer History Museum Page 6 of 25, Jonathan Bowen
Hoare: College life was wonderful. I think that the atmosphere of colleges in those days encouraged
quite intense and long lasting friendships among people studying in the same courses, and different
courses. I’ve kept up some of them all my life.
Bowen: Are there any particular people you’d like to mention?
Hoare: Perhaps Michael Jackson, who has worked all of his life in the area of computing, along lines
very similar to myself. I think I excited his first interest in mathematical logic as an object of study, so
maybe I had an influence on him as well.
https://lefenetrou.blogspot.com/2024/07/michael-jackson-langlais-les-native.html
"Jackson was educated at Harrow School in Harrow, London, England. There he was taught by Christopher Strachey and wrote his first program under Strachey's guidance. From 1954 to 1958, he studied classics (known as "Greats") at Merton College, Oxford;[2] a fellow student, two years ahead of him, was C. A. R. Hoare. They shared an interest in logic, which was studied as part of Greats at Oxford. " https://en.wikipedia.org/wiki/Michael_A._Jackson_(computer_scientist)
Les compétences de Strachey sont si élevées que Turing lui remet de facto la supervision des programmes de recherche informatique
« Je considère les problèmes syntaxiques comme essentiellement non pertinents pour les langages de programmation... En gros il me semble correct de penser que la sémantique est là pour ce que nous voulons dire et la syntaxe pour comment nous avons à le dire. »
https://fr.wikipedia.org/wiki/Christopher_Strachey
Bowen: Indeed, do you remember your first meeting?
Hoare: First meeting with Michael Jackson, no. I do remember one meeting when I explained to him
how the ancestral relation worked, the transitive closure of a relation in mathematical logic
Bowen: So were they quite serious meetings you had together?
Hoare: Yes, I was meeting him regularly as a sort of tutor for several weeks on end.
Bowen: It was just an informal arrangement?
Hoare: Completely informal, yes, yes.
Bowen: Was that normal thing to happen at Oxford at that time?
Hoare: I wouldn’t suppose it was abnormal.
Bowen: So you moved from classics to computing. What was the first program you ever wrote?
Hoare: I attended a programming course, which was run at Oxford University when I was a graduate
student, and it was run by Lesley Fox, who was a very distinguished numerical analyst. He was in fact
my Head of department when I first went to Oxford in 1977. But back in 1958 I attended a course inMercury Autocode, which was the programming language used on a computer that the University was just purchasing from Ferranti. I wrote a program. I chose my own exercise program. It was a solution of two person game, using a technique which I found in a book on game theory by von Neumann and Morgenstern. It did, I think-- well, I don’t know whether it worked or not. It certainly ran to the end, but I forgot to put in any check on whether the answers it produced was correct, and the calculations were too difficult for me to do by hand afterwards.
Bowen: What was programming like in those days?
Hoare: Very different from today. The programs were all prepared on punched cards or paper tape. It
might take a day even to get them punched up from the coding sheets, and then submitted to a computer
again, probably in a batch, maybe the following day. It would take a long time if there were any faults in the program, to find out where they were.
Bowen: This was also the time when you moved from Queen’s University, Belfast, to Oxford.
Hoare: That’s right. The motivation for my move to Oxford was indeed partially supplied by my idea to
study the Oxford ideas on the semantics of programming languages again. I hoped that it would be
possible, using the Oxford techniques of defining semantics, to clarify the exact meaning of
communicating processes in a way that would be helpful to people writing programs in that idiom.
Bowen: And of course this was a very sad time, when Chris Strachey died, but I believe you knew him
before.
Hoare: Yes, I knew Christopher before. I had visited him at Oxford in fact, as a member of a visiting
panel commissioned by the Science Research Council to make a report on the work that he was doing at
the programming research group. It was a great loss.
Bowen: This led up to your CSP book in your own red and white book series in 1985, but you were also
working on other things. You were very much promoting a new formal notation that became known as Z at Oxford, although maybe you weren’t directly working on it. I understand you were involved in inviting Jean-Raymond Abrial for instance, who very much promoted Z and defined Z. Would you like to say something about how that started?
Hoare: Yes, it’d be a pleasure. I met Jean-Raymond Abrial at a summer school organized by Electricite
de France in a lovely little village in France called Labrae sonnalp [sp] (1). I was very impressed by his research, and indeed his lecturing. He was a brilliant lecturer. I invited him to spend some research time at Oxford, and got a research grant for him from the Research Council. He did marvelous work in the development of Z. This is a sort of specialization of the techniques of logic and set theory, which were originally thought of as the foundation of mathematics in the earlier part of the last century, and now being suggested as a suitable notation and conceptual framework for specifying the desired properties of computer systems. The formal theory was adapted for this purpose and tried out in a number of small and other realistic and large sized examples, and found to be surprisingly effective at describing what a program is intended to do, rather than how the program works, how the program actually does it.
Bowen: I think you were involved with encouraging IBM to actually take up the ideas. How did that
come about?
Hoare: Again, it was very much a matter of chance. I was invited to give a keynote address at the British Computer Society Symposium on professionalism, I think it was, in programming. I talked a bit about formalization and verification, and put forward a conjecture, fairly tentatively, that maybe the time was right to scale these things up by trial use in industry. In the audience there happened to be quite a senior director from IBM at Hursley. He came up to me after the lecture, and invited me to put my commitment where my mouth was, and actually do something in collaboration with IBM. That made me gulp a bit, because I knew that -- well, I had the impression -- that IBM had produced some pretty complicated software, and this really would be a challenge, and there was a good chance that we would fall flat on our faces. But you can’t turn down an opportunity like that. So Abrial and Ib Sorensen and other colleagues set to work, and actually produced some very useful analyses for them, using Z, to help them with an ongoing project for restructuring and rewriting parts of their software system, a software system called CICS, C-I-C-S. It stands for Customer Information Control System. It was one of the most profitable and influential software products in those days, so it was an important project.
Bowen: That led to a Queen’s award for technology. Another strand of your work led to another
Queen’s award, which was the work on Occam and the transputer, which came out of your CSP work.
How did that connect ? "
(1) Ce nom de village n'existe pas. Certainement un problème de prononciation du français.
Lisez l'interview de Jonathan Bowen,
Merci Jonathan pour tout ce que tu fais encore aujourd'hui du U.K. jusqu'en Chine !
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