# Jan Lukasiewicz

**Jan Łukasiewicz**(21 December, 1878 - 13 February, 1956) was a mathematician born in Lvov. His major mathematical work centred on mathematical logic. He thought innovatively about traditional propositional logic, the principle of non-contradiction and the Law of excluded middle. Łukasiewicz worked on multi-valued logics, including his own three-valued propositional calculus, the first non-classical logical calculus. He is responsible for one of the most elegant axiomatizations of classical propositional logic; it has just three axioms and is one of the most used axiomatizations today. He also pursued philosophy, approaching the human aspects of scientific theory-making with ideas similar to those of Karl Popper.

Łukasiewicz's Polish Notation of 1920 was at the root of the idea of the *recursive stack* a last-in, first-out computer memory store invented by Charles Hamblin of the New South Wales University of Technology (NSWUT), and first implemented in 1957. This design led to the English Electric multi-programmed KDF9 computer system of 1963, which had two such hardware register stacks. A similar concept underlies the Reverse Polish Notation (or postfix notation) of Hewlett Packard calculators.

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## Life Events

- 1878 Born
- 1890-1902 Studies with Kazimierz Twardowski in Lvov
- 1902 Doctorate (mathematics and philosophy), University of Lvov with the highest distinction possible
- 1906 Habilitation thesis completed, University of Lvov
- 1906 Becomes a lecturer
- 1910 essays on the principle of non-contradiction and the excluded middle
- 1911 extraordinary professor at Lvov
- 1915 invited to the newly reopend University of Warsaw
- 1916 new Kingdom of Poland declared
- 1917 Develops three-valued propositional calculus
- 1919 Polish Minister of Education
- 1920-39 professor at Warsaw University founds with Stanislaw Leśniewski the Warsaw School of Logic (see also Alfred Tarski, Stefan Banach, Hugo Steinhaus, Zygmunt Janiszewski, Stefan Mazurkiewicz)
- ???? marries Regina Barwinska
- 1946 exile in Belgium
- 1946 offered a chair by the University of Dublin
- 1953 writes autobiography
- 1956 Dies in Dublin

## External Links

## Reading

- Aristotle & Łukasiewicz on the Principle of Contradiction, ed. by Frederick Seddon (Modern Logic, 1996) ASIN 1884905048
- Philosophical Logic in Poland, ed. by Jan Wolenski (Kluwer, 1994) ISBN 0792322932