Ole-Johan Dahl

Ole-Johan Dahl
Associated organizations
University of Oslo
Fields of study
ACM A.M. Turing Award


When Ole-Johan Dahl and Kristen Nygaard created the Simula languages in the 1960s at the Norwegian Computing Center, they introduced a new way of modeling and programming complex tasks. Object-oriented programming is now dominant in system development, and is everywhere part of the computer science curricula, as are languages built on OOP concepts, such as Smalltalk, C++, Eiffel and Java.

Kristen Nygaard analyzed complex problems by computer simulation, requiring interaction between many very dissimilar components. He saw the need for a description language that could be used to comprehend, describe and communicate complex systems, and also make it possible for computers to execute models of what had been described.

Ole-Johan Dahl joined Kristen Nygaard at the NCC. They designed the Simula concepts and language together, and Dahl carried out the difficult task of writing the program that translated descriptions into computer instructions. In 1968 Dahl became the University of Oslo’s first computer science professor and built its Informatics Department. Later he has contributed to the theory of proving correctness of programs. Nygaard continued OOP, but also became the driving force in the “Scandinavian school of system development.” His efforts now are aimed at improving the teaching and conceptual platform for computer science. Dahl and Nygaard are Professors Emeriti at the University of Oslo. They both have been named Commander of the Orderof Saint Olav by the King of Norway and Honorary Fellows ofthe Object Management Group, have received the Norwegian Rosing Prize and the 2001 ACM A.M. Turing Award.