Edsger Wybe Dijkstra was one of the most influential members of computing science's founding generation. Among the domains in which his scientific contributions are fundamental are
formal specification and verification
design of mathematical arguments
In addition, Dijkstra was intensely interested in teaching, and in the relationships between academic computing science and the software industry.
During his forty-plus years as a computing scientist, which included positions in both academia and industry, Dijkstra's contributions brought him many prizes and awards, including computing science's highest honor, the ACM Turing Award.
Like most of us, Dijkstra always believed it a scientist's duty to maintain a lively correspondence with his scientific colleagues. To a greater extent than most of us, he put that conviction into practice. For over four decades, he mailed copies of his consecutively numbered technical notes, trip reports, insightful observations, and pungent commentaries, known collectively as "EWDs", to several dozen recipients in academia and industry. Thanks to the ubiquity of the photocopier and the wide interest in Dijkstra's writings, the informal circulation of many of the EWDs eventually reached into the thousands.
Although most of Dijkstra's publications began life as EWD manuscripts, the great majority of his manuscripts remain unpublished. They have been inaccessible to many potential readers, and those who have received copies have been unable to cite them in their own work. To alleviate both of these problems, the department has collected over a thousand of the manuscripts in this permanent web site, in the form of PDF bitmap documents (to read them, you'll need a copy of Acrobat Reader). We hope you will find it convenient, useful, inspiring, and enjoyable.
The original manuscripts, along with diaries, correspondence, photographs, and other papers, are housed at The Center for American History of The University of Texas at Austin.
Each manuscript file is accessible through either of two indexes:
0. BibTeX index. Each entry includes all the available bibliographic data.
1. Ad-hoc indexes. These contain titles only, but are faster if you know what you're looking for.
EWD-numbered documents(This index gives an approximate correspondence between manuscripts' EWD numbers and the year in which they appeared.)
Technical reports from the Mathematical Centre (now CWI: Centrum voor Wiskunde en Informatica)
You can find a table relating EWD numbers to publication years here.
Many of the privately circulated manuscripts collected here were subsequently published; their copyrights are held by their respective publishers.
Transcripts and translations
A growing number of the PDF bitmap documents have been transcribed to make them searchable and accessible to visitors who are visually impaired.
A few of the manuscripts written in Dutch have been translated into English, and one has been translated into Spanish.
For these transcriptions and translations we are grateful to over sixty contributors. Volunteers willing to transcribe manuscripts are always welcome (Note: doing EWDs justice in translation has turned out to be too difficult, so we are no longer soliciting translations).
Proofreading Each transcription gets a cursory scan as it's prepared for uploading, but since a web page can always be updated, I don't strive for (unattainable) perfection before installing it. On the web, proofreading is a game that can be played by every reader; if you spot an error, please
Links between EWDs
A compilation of cross-references has been contributed by Diethard Michaelis. As its author notes, the collection is incomplete, and all readers are invited to add to it.
Dijkstra often returned to topics about which he had already written, when he had something new to say or even just a better way of saying it. When Dijkstra himself didn't provide the backward references, we indicate the relationship by "see also" links in the index, leaving the judgment of the extent to which the earlier EWD is superseded by the later one to the reader. Any reader who notices such a relationship is invited to
We have begun adding summaries of the EWDs. This innovation was suggested by Günter Rote, who contributed the first dozen summaries. Additional contributions of summariesespecially summaries in English of EWDs in Dutchare most welcome.
Video and audio
In addition to the manuscripts, you may enjoy some recordings of Dijkstra lectures and interviews.
About Dijkstra and his work
An interview with Dijkstra (Spanish translation here) was conducted in 1985 by Rogier F. van Vlissingen, who has also written a personal reflection on "Dijkstra's sense of what computer science and programming are and what they aren't".
Another interview was conducted by Philip L. Frana in August 2001. A transcript is available in the on-line collection of the Charles Babbage Institute.
To mark the occasion of Dijkstra's retirement in November 1999 from the Schlumberger Centennial Chair in Computer Sciences, which he had occupied since 1984, and to celebrate his forty-plus years of seminal contributions to computing science, the Department of Computer Sciences organized a symposium, In Pursuit of Simplicity, which took place on his birthday in May 2000. The symposium's program (10 MB) contains an outline of Dijkstra's career, as well as a collection of quotes culled from his writings, from his blackboard, and from what others have said about him. Banquet speeches by David Gries, Fred Schneider, Krzysztof Apt, W.M. Turski, and H. Richards were recorded on a video.
A remembrance of Dijkstra was posted in May 2008 by Maarten van Emden (thanks to Tristram Brelstaff for noting it).
A blog devoted to Dijkstras works and thoughts has been created, and is being maintained, by the historian of computing Edgar G. Daylight. An article by Daylight, Dijkstra's Rallying Cry for Generalization: the Advent of the Recursive Procedure, late 1950s - early 1960s, appeared in The Computer Journal, March 2011.
In his blog A Programmers Place, Maarten van Emden has an entry entitled Another scoop by Dijkstra?. The entry describes Dijkstras remarkable insight [in Notes on Structured Programming (EWD 249)] that resolves the stand-off between the Sieve of Eratosthenes (efficient in terms of time, but not memory) and the method of Trial Division (efficient in terms of memory, but not time) by applying the Assembly-line Principle.
The Edsger W. Dijkstra Prize in Distributed Computing honors Dijkstra’s “foundational work on concurrency primitives (such as the semaphore), concurrency problems (such as mutual exclusion and deadlock), reasoning about concurrent systems, and self-stabilization [, which] comprises one of the most important supports upon which the field of distributed computing is built.”
Recent significant changes in the site are listed here; the most recent change was posted on 5 April 2008.
The folks who contributed most significantly to the site's creation are acknowledged here.
Comments and suggestions about the site are always welcome; please email them to
If you find this site interesting, you may also be interested in another site:
Discipline in Thought which is a website dedicated to disciplined thinking, calculational mathematics, and mathematical methodology. The members of this site are markedly influenced by the works of EWD, and the material shared through the website continues in the traditions set by EWD (among others).