Edsger Dijkstra citations (71 citations)

Dijkstra (1972) The Humble Programmer http://www.cs.utexas.edu/users/EWD/transcriptions/EWD03xx/EWD340.html (EWD340). 1970s Contexte: After having programmed for some three years, I had a discussion with A. van Wijngaarden, who was then my boss at the Mathematical Center in Amsterdam, a discussion for which I shall remain grateful to him as long as I live. The point was that I was supposed to study theoretical physics at the University of Leiden simultaneously, and as I found the two activities harder and harder to combine, I had to make up my mind, either to stop programming and become a real, respectable theoretical physicist, or to carry my study of physics to a formal completion only, with a minimum of effort, and to become....., yes what? A programmer? But was that a respectable profession? For after all, what was programming? Where was the sound body of knowledge that could support it as an intellectually respectable discipline? I remember quite vividly how I envied my hardware colleagues, who, when asked about their professional competence, could at least point out that they knew everything about vacuum tubes, amplifiers and the rest, whereas I felt that, when faced with that question, I would stand empty-handed. Full of misgivings I knocked on van Wijngaarden’s office door, asking him whether I could “speak to him for a moment”; when I left his office a number of hours later, I was another person. For after having listened to my problems patiently, he agreed that up till that moment there was not much of a programming discipline, but then he went on to explain quietly that automatic computers were here to stay, that we were just at the beginning and could not I be one of the persons called to make programming a respectable discipline in the years to come? This was a turning point in my life and I completed my study of physics formally as quickly as I could. One moral of the above story is, of course, that we must be very careful when we give advice to younger people; sometimes they follow it!

“As a result, the topic became – primarily in the USA – prematurely known as ‘computer science’ – which, actually, is like referring to surgery as ‘knife science’ – and it was firmly implanted in people’s minds that computing science is about machines and their peripheral equipment. Quod non”

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Edsger W. Dijkstra

Dijkstra (1986) On a cultural gap http://www.cs.utexas.edu/users/EWD/transcriptions/EWD09xx/EWD924.html (EWD 924). 1980s Contexte: A confusion of even longer standing came from the fact that the unprepared included the electronic engineers that were supposed to design, build and maintain the machines. The job was actually beyond the electronic technology of the day, and, as a result, the question of how to get and keep the physical equipment more or less in working condition became in the early days the all-overriding concern. As a result, the topic became – primarily in the USA – prematurely known as ‘computer science’ – which, actually, is like referring to surgery as ‘knife science’ – and it was firmly implanted in people’s minds that computing science is about machines and their peripheral equipment. Quod non [Latin: "Which is not true"]. We now know that electronic technology has no more to contribute to computing than the physical equipment. We now know that programmable computer is no more and no less than an extremely handy device for realizing any conceivable mechanism without changing a single wire, and that the core challenge for computing science is hence a conceptual one, viz., what (abstract) mechanisms we can conceive without getting lost in the complexities of our own making.

“Program testing can be used to show the presence of bugs, but never to show their absence!”

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Edsger W. Dijkstra

Dijkstra (1970) " Notes On Structured Programming http://www.cs.utexas.edu/users/EWD/ewd02xx/EWD249.PDF" (EWD249), Section 3 ("On The Reliability of Mechanisms"), corollary at the end. 1970s Variante: Program testing can be a very effective way to show the presence of bugs, but it is hopelessly inadequate for showing their absence.

“The question of whether Machines Can Think… is about as relevant as the question of whether Submarines Can Swim.”

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Edsger W. Dijkstra

Dijkstra (1984) The threats to computing science http://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/EWD898.html (EWD898). 1980s

“The required techniques of effective reasoning are pretty formal, but as long as programming is done by people that don't master them, the software crisis will remain with us and will be considered an incurable disease. And you know what incurable diseases do: they invite the quacks and charlatans in, who in this case take the form of Software Engineering gurus.”

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Edsger W. Dijkstra

Dijkstra (2000) "Answers to questions from students of Software Engineering" http://www.cs.utexas.edu/users/EWD/transcriptions/EWD13xx/EWD1305.html (EWD 1305). 2000s

“The effective exploitation of his powers of abstraction must be regarded as one of the most vital activities of a competent programmer.”

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Edsger W. Dijkstra

1970s, The Humble Programmer (1972)

“Elegance is not a dispensable luxury but a quality that decides between success and failure.”

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Edsger W. Dijkstra

1990s

“I mean, if 10 years from now, when you are doing something quick and dirty, you suddenly visualize that I am looking over your shoulders and say to yourself "Dijkstra would not have liked this", well, that would be enough immortality for me.”

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Edsger W. Dijkstra

Dijkstra (1995) "Introducing a course on calculi" http://www.cs.utexas.edu/users/EWD/ewd12xx/EWD1213.PDF (EWD 1213). 1990s

“For me, the first challenge for computing science is to discover how to maintain order in a finite, but very large, discrete universe that is intricately intertwined. And a second, but not less important challenge is how to mould what you have achieved in solving the first problem, into a teachable discipline: it does not suffice to hone your own intellect (that will join you in your grave), you must teach others how to hone theirs. The more you concentrate on these two challenges, the clearer you will see that they are only two sides of the same coin: teaching yourself is discovering what is teachable.”

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Edsger W. Dijkstra

Dijkstra (1979) My hopes of computing science http://www.cs.utexas.edu/users/EWD/transcriptions/EWD07xx/EWD709.html (EWD 709). 1970s

“Industry suffers from the managerial dogma that for the sake of stability and continuity, the company should be independent of the competence of individual employees. Hence industry rejects any methodological proposal that can be viewed as making intellectual demands on its work force. Since in the US the influence of industry is more pervasive than elsewhere, the above dogma hurts American computing science most. The moral of this sad part of the story is that as long as computing science is not allowed to save the computer industry, we had better see to it that the computer industry does not kill computing science.”

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Edsger W. Dijkstra Computing Science

Dijkstra (1999) "Computing Science: Achievements and Challenges" https://www.cs.utexas.edu/users/EWD/transcriptions/EWD12xx/EWD1284.html (EWD 1284). 1990s

“It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration.”

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Edsger W. Dijkstra

1970s, How do we tell truths that might hurt? (1975)

“Please don't fall into the trap of believing that I am terribly dogmatic about [the go to statement]. I have the uncomfortable feeling that others are making a religion out of it, as if the conceptual problems of programming could be solved by a simple trick, by a simple form of coding discipline!”

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Edsger W. Dijkstra

Dijkstra (1973) in personal communication to Donald Knuth, quoted in Knuth's "Structured Programming with go to Statements".
1970s

“It is not the task of the University to offer what society asks for, but to give what society needs.”

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Edsger W. Dijkstra

Dijkstra (2000), "Answers to questions from students of Software Engineering" http://www.cs.utexas.edu/~EWD/ewd13xx/EWD1305.PDF (EWD 1305). 2000s

“Thank goodness we don't have only serious problems, but ridiculous ones as well.”

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Edsger W. Dijkstra

Dijkstra (1982) "A Letter to My Old Friend Jonathan" (EWD475) p. 101 in [Dijkstra, Edsger, Selected Writings on Computing, Springer-Verlag, Berlin, 1982, 9780387906522]
1980s

“A convincing demonstration of correctness being impossible as long as the mechanism is regarded as a black box, our only hope lies in not regarding the mechanism as a black box.”

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Edsger W. Dijkstra

Dijkstra (1970) " Notes On Structured Programming http://www.cs.utexas.edu/users/EWD/ewd02xx/EWD249.PDF" (EWD249), Section 3 ("On The Reliability of Mechanisms"), p. 5. 1970s

“Simplicity is a great virtue but it requires hard work to achieve it and education to appreciate it. And to make matters worse: complexity sells better.”

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Edsger W. Dijkstra

Dijkstra (1984) On the nature of Computing Science http://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/EWD896.html (EWD896). 1980s

“A picture may be worth a thousand words, a formula is worth a thousand pictures.”

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Edsger W. Dijkstra

Dijkstra (EWD1239: A first exploration of effective reasoning)
1990s

“Another two years later, in 1957, I married and Dutch marriage rites require you to state your profession and I stated that I was a programmer. But the municipal authorities of the town of Amsterdam did not accept it on the grounds that there was no such profession. And, believe it or not, but under the heading “profession” my marriage act shows the ridiculous entry “theoretical physicist!””

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Edsger W. Dijkstra

Dijkstra (1972) The Humble Programmer http://www.cs.utexas.edu/users/EWD/transcriptions/EWD03xx/EWD340.html (EWD340). 1970s

“Simplicity is prerequisite for reliability.”

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Edsger W. Dijkstra

1970s, How do we tell truths that might hurt? (1975)

“When we take the position that it is not only the programmer's responsibility to produce a correct program but also to demonstrate its correctness in a convincing manner, then the above remarks have a profound influence on the programmer's activity: the object he has to produce must be usefully structured.”

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Edsger W. Dijkstra

Dijkstra (1970) " Notes On Structured Programming http://www.cs.utexas.edu/users/EWD/ewd02xx/EWD249.PDF" (EWD249), Section 3 ("On The Reliability of Mechanisms"), p. 6. 1970s

“We must not forget that it is not our [computing scientists'] business to make programs, it is our business to design classes of computations that will display a desired behaviour.”

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Edsger W. Dijkstra

1970s, The Humble Programmer (1972)

“How do we convince people that in programming simplicity and clarity —in short: what mathematicians call "elegance"— are not a dispensable luxury, but a crucial matter that decides between success and failure?”

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Edsger W. Dijkstra

1980s
Source: EWD648.

“There are very different programming styles. I tend to see them as Mozart versus Beethoven. When Mozart started to write, the composition was finished. He wrote the manuscript and it was 'aus einem Guss' (from one cast). In beautiful handwriting, too. Beethoven was a doubter and a struggler who started writing before he finished the composition and then glued corrections onto the page. In one place he did this nine times. When they peeled them, the last version proved identical to the first one.”

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Edsger W. Dijkstra

Dijkstra (2001) Source: Denken als discipline https://www.youtube.com/watch?v=-Uae9_pgZzE#t=280, a program from Dutch public TV broadcaster VPRO from April 10th, 2001 about Dijkstra 2000s

“One moral of the above story is, of course, that we must be very careful when we give advice to younger people; sometimes they follow it!”

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Edsger W. Dijkstra

“Automatic computers have now been with us for a quarter of a century. They have had a great impact on our society in their capacity of tools, but in that capacity their influence will be but a ripple on the surface of our culture, compared with the much more profound influence they will have in their capacity of intellectual challenge without precedent in the cultural history of mankind.”

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Edsger W. Dijkstra

Dijkstra (1972) The Humble Programmer http://www.cs.utexas.edu/users/EWD/transcriptions/EWD03xx/EWD340.html (EWD340). 1970s

“Besides a mathematical inclination, an exceptionally good mastery of one's native tongue is the most vital asset of a competent programmer.”

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Edsger W. Dijkstra

1970s, How do we tell truths that might hurt? (1975)

“I think of the company advertising "Thought Processors" or the college pretending that learning BASIC suffices or at least helps, whereas the teaching of BASIC should be rated as a criminal offence: it mutilates the mind beyond recovery.”