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.
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 precludes roundoff error.
He was involved with developing international standards in programming and informatics, as a member of the International Federation for Information Processing (IFIP) IFIP Working Group 2.1 on Algorithmic Languages and Calculi,[1][2] which specified, maintains, and supports the programming languages ALGOL 60 and ALGOL 68.
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