Eric Hehner

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.