Edsger W. Dijkstra

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File:Edsger Dijkstra large.jpg
Edsger Dijkstra (courtesy Brian Randell)

Prof Dr Edsger Wybe Dijkstra (Rotterdam, May 11, 1930Nuenen, August 6, 2002; IPA: [ˈɛtˌsxər ˈdɛɪkˌstra]) was a Dutch computer scientist. He received the 1972 A. M. Turing Award for fundamental contributions in the area of programming languages, and was the Schlumberger Centennial Chair of Computer Sciences at The University of Texas from 1984 until his death in 2002.

Life

Dijkstra studied theoretical physics at the University of Leiden, but he quickly realized he was more interested in programming than physics.

Originally employed by the Mathematisch Centrum in Amsterdam, he held a professorship at the Eindhoven University of Technology in the Netherlands, worked as a research fellow for Burroughs Corporation in the early 1970s, and later held the Schlumberger Centennial Chair in Computer Sciences at the University of Texas at Austin, in the United States. He retired in 2000.

Among his contributions to computer science is the shortest path-algorithm, also known as Dijkstra's algorithm, and the semaphore construct, for coordinating multiple processors and programs. Another concept due to Dijkstra in the field of distributed computing is that of self-stabilization - an alternative way to ensure the reliability of the system.

He was also known for his low opinion of the GOTO statement in computer programming, culminating in the 1968 article "Go To Statement Considered Harmful" (EWD215) [1], regarded as a major step towards the widespread deprecation of the GOTO statement and its effective replacement by control structures such as the while loop. The paper's famous title was not the work of Dijkstra, but of Niklaus Wirth, then editor of Communications of the ACM. Dijkstra was known to be a fan of ALGOL 60, and worked on the team that implemented the first compiler for that language. Dijkstra and Jaap Zonneveld, who collaborated on the compiler, agreed not to shave until the project was completed. Zonneveld eventually shaved off his beard; Dijkstra kept his until his death.

From the 1970s, Dijkstra's chief interest was formal verification. The prevailing opinion at the time was that one should first write a program and then provide a mathematical proof of correctness. Dijkstra objected that the resulting proofs are long and cumbersome, and that the proof gives no insight as to how the program was developed. An alternative method is program derivation, to "develop proof and program hand in hand". One starts with a mathematical specification of what a program is supposed to do and applies mathematical transformations to the specification until it is turned into a program that can be executed. The resulting program is then known to be correct by construction. Much of Dijkstra's later work concerns ways to streamline mathematical argument. In a 2001 interview, he stated a desire for "elegance," whereby the correct approach would be to process thoughts mentally, rather than attempt to render them until they are complete. The analogy he made was to contrast the compositional approaches of Mozart and Beethoven.

Dijkstra was known for his forthright opinions on programming, and for his habit of carefully composing manuscripts with his fountain pen. The manuscripts are called EWDs, since Dijkstra numbered them with EWD as prefix. Dijkstra would distribute photocopies of a new EWD among his colleagues; as many recipients photocopied and forwarded their copy, the EWDs spread throughout the international computer science community (see EWD1000). The topics are mainly computer science and mathematics, but also include trip reports, letters, and speeches. Many of the more than 1300 EWDs have since been scanned and are available online.

He died on August 6, 2002 after a long struggle with cancer.

Andrzej Sapkowski, Polish fantasy writer, used Dijkstra's name for one of the main character in the five book "Saga" about The Hexer.

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