Eric Hehner

Eric C. R. Hehner
Born	16 September 1947 (1947-09-16) (age 77) Ottawa, Ontario
Nationality	Canadian
Alma mater	Carleton University, University of Toronto
Scientific career
Fields	Formal methods, Programming
Institutions	University of Toronto

Eric C.R. Hehner, called Rick, is a Canadian computer scientist. He was born on 16 September 1947 in Ottawa. He studied mathematics and physics at Carleton University, graduating in 1969. He gained a PhD in computer science from the University of Toronto in 1974. He then joined the faculty there, becoming a full professor in 1983. He became the Bell University Chair in Software Engineering in 2001, and retired in 2012.

Hehner's main research area is formal methods of software design. His method, initially called predicative programming, later called Practical Theory of Programming, is to consider each specification to be a binary (boolean) expression, and each programming construct to be a binary expression specifying the effect of executing the programming construct. Refinement is just implication. This is the simplest formal method, and the most general, applying to sequential, parallel, stand-alone, communicating, terminating, nonterminating, natural-time, real-time, deterministic, and probabilistic programs, and includes time and space bounds. This idea has influenced other computer science researchers, including Tony Hoare.

Hehner's other research areas include probabilistic programming, unified algebra, and high-level circuit design. In 1979, Hehner invented a generalization of radix complement called quote notation, which is a representation of the rational numbers that allows easier arithmetic and produces no roundoff error.

References

• E. C. R. Hehner, 1984. Predicative Programming. CACM, 27(2):134–151.
• E. C. R. Hehner, 1990. A Practical Theory of Programming. Science of Computer Programming, 14(2–3):133–158.
• E. C. R. Hehner, 2004. From Boolean Algebra to Unified Algebra. Mathematical Intelligencer, 26(2):3–19.
• "A new representation of the rational numbers for fast easy arithmetic", E.C.R. Hehner and R.N.S. Horspool

External links

• Home page
• DBLP publications
• A Practical Theory of Programming, Professor Hehner's book, freely available in PDF
• Eric Hehner archival papers held at the University of Toronto Archives and Records Management Services