Peter Naur: 1928-2016

Peter Naur, a Danish computer scientist and 2005 recipient of the ACM A.M. Turing Award for fundamental contributions to programming language design and the definition of Algol 60, to compiler design, and to the art and practice of computer programming, died January 3 after a brief illness.

Born in Fredricksberg, Denmark, Naur studied astronomy at the University of Copenhagen, where he received his Ph.D. in that field before going to Kings College Cambridge in the 1950s to conduct research both into astronomy and the emerging field of computer programming. As he told Computerworld Denmark in a 2014 interview (http://bit.ly/1O13v1I), "I had the great privilege to get to Cambridge in the early 1950s. Here I discovered that calculations of planetary motion that could take several hours, could now be carried out in seconds with a computer."

As a result, Naur changed his career focus to computer science. From 1959 to 1969, he worked at Denmark’s Regnecentralen computing institute (now known as the Danish Institute of Mathematical Machines), while he was also lecturing at the Niels Bohr Institute and the Technical University of Denmark.

At the Regnecentralen, Naur participated in the development of a programming language that came to be known as Algol 60. He became the main author of the Report on the Algorithmic Language ALGOL 60 (http://web.eecs.umich.edu/~bchandra/courses/papers/Naure_Algol60.pdf) and made the decision, which was controversial at the time, to include recursion.

In 1969, Naur was appointed professor at the Institute of Datalogi at Copenhagen University, a post he held until his retirement in 1999 at the age of 70. His main areas of inquiry were design, structure, and performance of computer programs and algorithms.

"Computing presents us a form of description … very useful for describing a great variety of phenomena of this world, but human thinking is not one of them."

In his book Computing: A Human Activity (1992), Naur rejected the formalist view of programming as a branch of mathematics. He did not like being associated with the Backus-Naur Form (a notation technique for context-free grammars attributed to him by Donald Knuth), and said he would prefer it to be called the Backus Normal Form.

Naur disliked the term "computer science," suggesting it instead be called "datalogy" or "data science" ("dataology" has been adopted in Denmark and in Sweden as datalogi, while "data science" is used to refer to data analysis (as in statistics and databases).

In his 2005 ACM A.M. Turing Award Lecture (the full lecture is available for viewing at http://amturing.acm.org/vp/naur_1024454.cfm), Naur offered a 50-year retrospective of computing vs. human thinking. He concluded, "Computing presents us a form of description … very useful for describing a great variety of phenomena of this world, but human thinking is not one of them, the reason being that human thinking basically is a matter of the plasticity of the elements of the nervous system, while computers—Turing machines—have no plastic elements. For describing human thinking one needs a very different, non-digital form, as demonstrated by the Synapse-State Theory" (Naur’s theory documented in a February 2004 paper that defines "mental life" in terms of neural activity).

Google vice president and Chief Internet Evangelist Vint Cerf said, "I did not know Peter well but I was a beneficiary of his work. For many years, I made heavy use of the Backus-Naur Form to describe the syntax of languages and other constructs such as email formats. Peter’s insight, as I see it, was to provide us with a thoroughly general and regular way in which to express the structure of string-based objects. Conversion of this description into parsing programs that allowed applications to process these objects was made straightforward by simplicity of the BNF form."

Cerf, a former ACM president, added, "In later years, I would meet Peter at the newly created Heidelberg Laureate Forum and enjoyed so much his ideas, especially about the way in which the brain operates. He seemed to be onto some very intriguing notions and I am sorry to learn that he has passed away before he could pursue them more fully.

"The field of computer science benefited greatly from Peter’s contributions and his enthusiasm for the field. I will miss our annual meetings and will remember him with respect and admiration."