Edsger Wybe Dijkstra (1930–2002) was one of the most influential researchers in the history of computer science, making fundamental contributions to both the theory and practice of computing. Early in his career, he proposed the single-source shortest path algorithm, now commonly referred to as Dijkstra’s algorithm. He wrote (with Jaap Zonneveld) the first ALGOL 60 compiler, and designed and implemented with his colleagues the influential THE operating system. Dijkstra invented the field of concurrent algorithms, with concepts such as mutual exclusion, deadlock detection, and synchronization. A prolific writer and forceful proponent of the concept of structured programming, he convincingly argued against the use of the Go To statement. In 1972 he was awarded the ACM Turing Award for “fundamental contributions to programming as a high, intellectual challenge; for eloquent insistence and practical demonstration that programs should be composed correctly, not just debugged into correctness; for illuminating perception of problems at the foundations of program design.” Subsequently he invented the concept of self-stabilization relevant to fault-tolerant computing. He also devised an elegant language for nondeterministic programming and its weakest precondition semantics, featured in his influential 1976 book A Discipline of Programming in which he advocated the development of programs in concert with their correctness proofs. In the later stages of his life, he devoted much attention to the development and presentation of mathematical proofs, providing further support to his long-held view that the programming process should be viewed as a mathematical activity.
In this unique new book, 31 computer scientists, including five recipients of the Turing Award, present and discuss Dijkstra’s numerous contributions to computing science and assess their impact. Several authors knew Dijkstra as a friend, teacher, lecturer, or colleague. Their biographical essays and tributes provide a fascinating multi-author picture of Dijkstra, from the early days of his career up to the end of his life.
Tony Hoare was on the faculty of the Queen's University of Belfast from 1968 until 1977. He moved to Oxford University as Professor of Computation in 1977, where he remained until his retirement from academia in 1999. Shortly thereafter he joined the Microsoft Research Laboratory in Cambridge (UK). His research has spanned several aspects of programming including design of data structures and programming languages, program verification, and concurrency. He invented Quicksort, conceived Hoare logic, proposed (jointly with Per Brinch Hansen) the concept of a monitor, and introduced Communicating Sequential Processes both as a language for distributed programming and, later, as a formalism to reason about concurrency and nondeterminism. His more recent work is concerned with the Unifying Theories of Programming. Hoare received the Turing Award in 1980, the Harry H. Goode Memorial Award in 1981, the Kyoto Prize in 2000, and the IEEE John von Neumann Medal in 2011. In 2000, he was knighted by the British Queen for services to education and computer science. He holds honorary doctorates from several universities and is a fellow or foreign member of various learned societies, including the UK Royal Society, the UK Royal Academy of Engineering, the US National Academy of Sciences, the US National Academy of Engineering, and the Computer History Museum. Together with Krzysztof R. Apt, he is the editor of this volume.
