Program testing can be a very effective way to show the presence of bugs, but is hopelessly inadequate for showing their absence.
The Humble Programmer, ACM Turing Lecture 1972
Edsger Dijkstra:
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Edsger Dijkstra Frases famosas
The introduction of suitable abstractions is our only mental aid to reduce the appeal to enumeration, to organize and master complexity.
Selected writings on computing: a personal perspective - página 2, Edsger Wybe Dijkstra - Springer-Verlag, 1982, ISBN 0387906525, 9780387906522 - 362 páginas
Computer science is no more about computers than astronomy is about telescopes, biology is about microscopes or chemistry is about beakers and test tubes. Science is not about tools, it is about how we use them and what we find out when we do.
Fellows, M.R., and Parberry, I., "SIGACT trying to get children excited about CS", January 1993, Computing Research News.
Atribuídas
Edsger Dijkstra: Frases em inglês
Dijkstra (1996) "The next fifty years" https://www.cs.utexas.edu/users/EWD/transcriptions/EWD12xx/EWD1243a.html (EWD 1243a).
1990s
are not a dispensable luxury, but a crucial matter that decides between success and failure?
1980s
Fonte: EWD648.
Dijkstra (1972) The Humble Programmer http://www.cs.utexas.edu/users/EWD/transcriptions/EWD03xx/EWD340.html (EWD340).
1970s
Contexto: 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!
Dijkstra (1986) On a cultural gap http://www.cs.utexas.edu/users/EWD/transcriptions/EWD09xx/EWD924.html (EWD 924).
1980s
Contexto: 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!”
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.
Dijkstra (1984) The threats to computing science http://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/EWD898.html (EWD898).
1980s
Dijkstra (2000) "Answers to questions from students of Software Engineering" http://www.cs.utexas.edu/users/EWD/transcriptions/EWD13xx/EWD1305.html (EWD 1305).
2000s
Dijkstra (1995) "Introducing a course on calculi" http://www.cs.utexas.edu/users/EWD/ewd12xx/EWD1213.PDF (EWD 1213).
1990s
Dijkstra (1979) My hopes of computing science http://www.cs.utexas.edu/users/EWD/transcriptions/EWD07xx/EWD709.html (EWD 709).
1970s
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
Dijkstra (1973) in personal communication to Donald Knuth, quoted in Knuth's "Structured Programming with go to Statements".
1970s
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.”
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
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
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.”
Dijkstra (EWD1239: A first exploration of effective reasoning)
1990s
Dijkstra (1972) The Humble Programmer http://www.cs.utexas.edu/users/EWD/transcriptions/EWD03xx/EWD340.html (EWD340).
1970s
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
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
Dijkstra (1972) The Humble Programmer http://www.cs.utexas.edu/users/EWD/transcriptions/EWD03xx/EWD340.html (EWD340).
1970s
Contexto: 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!
Dijkstra (1972) The Humble Programmer http://www.cs.utexas.edu/users/EWD/transcriptions/EWD03xx/EWD340.html (EWD340).
1970s
1970s, How do we tell truths that might hurt? (1975)
Dijkstra (1984) Source: The threats to computing science http://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/EWD898.html (EWD898).
1980s
