Professor Charles Leonard Hamblin

An Australian philosopher, logician and a computer pioneer as well as a professor of philosophy at the Technical University of New South Wales (now the University of New South Wales) in Sydney. Among his most well-known achievements in the area of computer science was the introduction (some sources also say invention) of the Reverse Polish Notation and the invention of the stack in computing. This was arguably independent of and about the same time as the work of Friedrich Ludwig Bauer and Klaus Samelson on the invention of the push-pop stack. Hamblin's most well-known contribution to philosophy is his book Fallacies, a standard work in the area of the false conclusions in logic. After the Second World War and the radar service at the Australian Air Force was interrupted, he studied mathematics, physics and philosophy at the University of Melbourne and attained a doctorate in 1957 at the London School of Economics. From 1955 up to his death, he was a professor of philosophy at the University of New South Wales. In the second half of the 1950s, he became active with the third computer available in Australia, a copy of the DEUCE computer by the English Electric company. For the DEUCE, he sketched one of the first programming languages, GEORGE, which was based on Reverse Polish Notation, including the associated compiler (language translator), which translated the programs formulated in GEORGE into the machine language of the computer. His work is considered the first with reverse Polish notation, and this is why he is called an inventor of this representation method. Whether or not he independently invented the notation and its usage, he showed the merit, service and advantage of the Reverse Polish way of writing programs for the processing on programmable computers and algorithms to make it happen. The second direct result of his work with the development of compilers was the concept of the push-pop stack, which he developed independently of Friedrich Ludwig Bauer and Klaus Samelson, and for which in 1957 he was granted a patent for the use of a push-pop stack for the translation by programming languages. In the same year, 1957, he presented his stack concept at the first Australian Computer Conference. His work had an impact on the development of stack-based computers, their machine instructions, their arguments on a stack and reference addresses. Into the 1960s, he again increasingly turned to philosophical questions. Besides writing an influential introductory book into the formal logic which is today a standard work on fallacies. It dedicated itself to the treatment of false conclusions by the traditional logic and brought in it formal dialectic and developed it further. As such, he is considered as one the founders of the modern informal logic. He contributed to the development of modern temporal logic in two ways. In its very early period he corresponded with Arthur Prior between 1958 and 1965; this collaboration culminated with the so-called Hamblin implications. Later in 1972 he independently rediscovered a form of duration calculus (interval logic), without being aware of the 1947 work of A. G. Walker on this topic, who was not interested in the tense aspect. His duration calculus is very similar to that later developed by James Allen and Patrick J. Hayes in mid 1980s. In addition to ancient Greek, he was familiar with several Asian and Pacific languages. A classical music lover who played the piano, he was setting words of Wittgenstein to music while hospitalized with an affliction that proved fatal. Among his influential articles are: Translation to and from polish notation. The computer journal 5/3, October 1962, P. 210-213; An Addressless Coding Scheme based on Mathematical notation. W.R.E. Conference on Computing, proceedings, Salisbury: Weapons Research establishment 1957; GEORGE, an Addressless Coding Scheme for DEUCE. Australian national Committee on Computation and Automatic Control, Summarized Proceedings of First Conference, paper C6.1, 1960; and Computer Languages. The Australian journal of Science 20, P. 135-139. Reprinted in The Australian Computer Journal 17/4, P. 195-198 (November 1985).