# Jan Łukasiewicz

**Jan Łukasiewicz** (born 21 December, 1878 - 13 February, 1956) was a Polish mathematician born in Lwów, Galicia (now L'viv, Ukraine). 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, the Forth programming language, or the PostScript page description language.

## Life events

- 1878 Born
- 1890-1902 Studies with Kazimierz Twardowski in Lwów (L'viv)
- 1902 Doctorate (mathematics and philosophy), University of Lwów with the highest distinction possible
- 1906 Habilitation thesis completed, University of Lwów (L'viv)
- 1906 Becomes a lecturer
- 1910 essays on the principle of non-contradiction and the excluded middle
- 1911 extraordinary professor at Lwów (L'viv)
- 1915 invited to the newly reopened University of Warsaw
- 1916 new Kingdom of Poland declared
- 1917 Develops three-valued propositional calculus
- 1919 Polish Minister of Education
- 1920-1939 professor at Warsaw University founds with Stanisław Leśniewski the Lwów-Warsaw School of logic (see also Alfred Tarski, Stefan Banach, Hugo Steinhaus, Zygmunt Janiszewski, Stefan Mazurkiewicz)
- 1928 marries Regina Barwinska
- 1946 exile in Belgium
- 1946 offered a chair by the University College 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) ISBN 1884905048
- Philosophical Logic in Poland, ed. by Jan Wolenski (Kluwer, 1994) ISBN 0792322932
- Jan Łukasiewicz:
*Elements of Mathematical Logic*, Warsaw, Państwowe Wydawnictwo Naukowe, 1963 - Jan Łukasiewicz (1970).
*Selected Works*, North-Holland Pub. Co.. ISBN 0720422523.

de:Jan Łukasiewicz es:Jan Lukasiewicz ja:ヤン・ウカシェヴィチ pl:Jan Łukasiewicz ru:Лукасевич, Ян sl:Jan Łukasiewicz