Edsger Dijkstra Wybe ( Rotterdam , May 11 1930 - Nuenen , August 6 2002 ) was a Dutch mathematician and computer scientist . His work was of great importance for the development ofscience , particularly in the area of structured programming . In 1972 he was awarded the Turing Award .


 [ hide ] *1 Biography

Biography edit ]Edit

Dijkstra studied at Leiden University , where in 1951 he took his bachelor's in mathematics and physics , and in 1956 graduated in theoretical physics.

From 1952 to 1962 worked Dijkstra at the Mathematical Centre in Amsterdam as a scientific programmer, where he was hired to the ARRA I program. Later he developed the software forARMAC . In his time at CWI, he worked on a compiler for the programming language Algol 60 . In this work he received his beard: he and his employee Jaap Zonneveld had agreed not to shave until the work was finished. He wrote his doctoral thesis in 1958. [1] A year later he developed named after him kortstepadalgoritme .

Because of the deep impression he made ​​as a scientific programmer, Dijkstra was appointed in 1962 as professor at the Technical University of Eindhoven , where he continued to work. till 1984 During this time his focus was on the art and science of developing the computer on mathematical basis (which incidentally was also the title of one of the subjects he taught). In 1972 he received the Turing Award for his contributions to computer science in the 1950s. From 1982 he was also a fellow of the Burroughs Corporation .

In 1984 Dijkstra Eindhoven exchanged for the University of Texas at Austin in the U.S. . There he continued his work often, even in collaboration with his former colleagues and students from the Netherlands. Dijkstra continued working there until his retirement in 1999. Both during his work in the U.S. and after his retirement with his wife Dijkstra made ​​long journeys through the state and national parks of the country. For this, they used their Volkswagen van that they jokingly the "Touring Machine" (pun on Turing Machine ) called.

Dijkstra died at the age of 72 in Nuenen to colon cancer .

Contributions to Computer Science edit ]Edit

Dijkstra in his career a particularly large contribution to science , both in the number and scope of his contributions. His scientific work is more than 1,300 publications. This includes his famous EWD's (after his initials). These were documents that he wrote for himself, but suggested freely available. Photocopies of them found their way all over the world, and today many of these handwritten texts scanned. Of many EWD are transcriptions available in the EWDijkstra Archive of the University of Texas. [2]

Dijkstra treats compiler construction, design of control systems , design of programming languages ​​and algorithms, but his greatest contribution to the field was undoubtedly the mathematical foundations of computer science. Especially before Dijkstra took with his students in 1962 huge inspiration in a publication on predicatencalculus of Tony Hoare . This axiomatic basis for the development of computer programs Dijkstra has guided the entire science and art exalted a aanmodder-event into a real science. Dijkstra is regarded as one of the true fathers of computer science and as a direct successor of people like Alan Turing .

Dijkstra was a strong opponent of the GOTO command and has played an important role in the replacement by functions , loops and such structures. Nevertheless contained the source code written by Dijkstra Pascal-S many GOTO's.He was a key member of the group that the programming language Algol-60 developed and wrote for that language first practical compiler. He has many other contributions to the development of programming languages ​​and operating systems supplied.

Aphorisms edit ]Edit

In addition to his scientific work, Dijkstra was famous for its winged (and sometimes acrimonious) comments on the practice of his profession, as

  • APL is a mistake, carried through to perfection It is the language of the future for the programming techniques of the past:. it Creates a new generation of coding bums. "
  • "It is practically impossible to teach good programming to students thathave had a prior exposure to BASIC : as potential programmers they are mentally mutilated beyond hope of regeneration. "
  • "The use of COBOL cripples the mind; Should its teaching, Therefore, be Regarded as a criminal offense. "
  • "In their capacity as a tool, computers will be but a ripple on the surface of our culture. In their capacity as intellectual challenge, they are without precedent in the cultural history of mankind."
  • "Simplicity is prerequisite for reliability."
  • "The question of Whether Machines Can Think (...) is about as relevant as the question of Whether Submarines Can Swim."
  • "It is not the task of the University to offer what society asks for, but to give what society needs."

Dijkstra as a teacher edit ]Edit

Dijkstra was known as a charismatic teacher. His writings are very readable. The examples he uses are often very appealing and illustrative. The problem of cooperating processes, for example, he illustrated by means of a hair salon.

The salon edit ]Edit

The salon consists of a waiting room and a salon. If there are no customers, the barber sleep. Conduct for a haircut are:

  • as long as there are customers: cut a client in the salon
  • otherwise, go to sleep in the waiting room

And the rules of conduct for the customers:

  • if the barber is asleep: wake him
  • else: stay in the waiting room

The crux is in the sleeping barber in the waiting room. When an invisible sleeping barber customer sees no difference between a barber who is busy in the salon and a hairdresser at the salon is sleeping.

The wolf, sheep and cabbage edit ]Edit

Another example was the issue of "The wolf, sheep and cabbage", by which he illustrated how to make preservation of symmetry in a design problem solving easier.

The problem of the wolf, sheep and cabbage is a known problem for children: a shepherd has a wolf, a sheep and a cabbage. He comes to a river with a boat which he can turn. Himself and another thing about How he comes now with all trade on the other side without unwanted consumption?

The solution lies in realizing that the problem is symmetric in the sheep and the wolf and the cabbage basically the same thing: they can not stay alone with the sheep. We call S the sheep, the shepherd H and the wolf and the cabbage both A and we introduce the rule that we take delivery passages, no steps back then the problem is solved and there is only one solution. Described as a list of consecutive states on the left and right bank, where A (2) stands for "two elements A":

0) HSA (2) -
1) A (2) HS
2) HA (2) S
3) A HAS
4) HAS A
5) S HA (2)
6) HS A (2)
7) - HSA (2)