Jan Łukasiewicz

January Łukasiewicz [ jan ʲ wukaɕɛv itʃ ] ( born December 21, 1878 in Lviv, † February 13, 1956 in Dublin) was a Polish philosopher, mathematician and logician.

Work

Łukasiewicz was in the years from 1915 to 1939 professor at the University of Lviv and Warsaw, on the latter twice rector. His work there was characterized by the Lvov -Warsaw School, the University of Warsaw took their basic research on mathematical logic into a center of logic in the period after the First World War. Among his students and later colleagues included, among other Alfred Tarski. 1919 Łukasiewicz for a short period of Polish Minister of Education.

1938 awarded him the University of Muenster an honorary doctorate in philosophy. During the occupation that followed the German invasion of Poland, he worked at the secret underground Warsaw University ( Uniwersytet Warszawski Tajny ). The end of the war he experienced in Hembsen, whereas it had taken for his own safety befriended German mathematician. In 1949 he went to Dublin, where he was offered a professorship at the University and worked the rest of his life.

He led the later so-called Polish notation ( prefix notation ) one in which the operator of an expression is written (eg, a mathematical formula ) before the operands and the resulting works without parentheses: Instead of 8 5 8 5 to write Later, the reverse Polish notation ( postfix ) was derived therefrom, in which the operators are written after their operands (eg, 8 5 ).

January Łukasiewicz formalized in 1920 the three-valued logic L3, and so created the first multi-valued, and thus non-classical logical calculus. But his work also dealt with the classical logic. So he proved independently by Bernays and post the completeness and consistency of the classical propositional logic.

He used truth-value functions, which are now known as Łukasiewicz - Tarski - negation and Łukasiewicz - Tarski implication in his many-valued logics.

By Jan Łukasiewicz also originate pioneering work on the history of logic. He reconstructed the Aristotelian syllogistic and besides Martha Kneale discovered the importance of Stoic logic, which he believed to be the earliest historical form of propositional logic (now the priority is the " dialecticians " Diodorus Cronus and Philo of Megara attributed ). With this re-evaluation, he freed the Stoa of the old and stubborn judgment, they have introduced a barren formalism in the logic, and added the history of logic to a new chapter.

Works

• January Łukasiewicz, Alfred Tarski: studies of the propositional calculus, Comptes Rendus Séances Société des Sciences et Lettres Varsovie, Cl. III, 23 (1930 ), pp. 30-50.
• Jan Łukasiewicz: Philosophical Remarks on valued systems of the statement calculus. In: Comptes explanatory. séances d d l Soc. Sciences et Lettres d d d Vars. Cl. III. 1930
• January Łukasiewicz: Z historii logiki Ždáň. In: Przegl. filoz. 37 (1934 ), pp. 417-437 ( Eng.:. History of the propositional logic in: knowledge, Volume 5, 1935, pp. 111-131 ). ( Discovery of the Stoic Junktorenlogik )
• January Łukasiewicz: Aristotle 's syllogistic. From the standpoint of modern formal logic. Oxford: Clarendon Press, 1951.
• January Łukasiewicz: Elements of mathematical logic. Transl. from the Polish by Olgierd Wojtasiewicz. Oxford [ ua]: Pergamon Press / Warszawa: Wydawnictwo Państwowe Naukowe, 1963 ( = boarding Series of monographs on pure and applied mathematics, 31. ). ( Ubs. of ' Elementy logiki matemtycznej ')
• January Łukasiewicz: Selected works. Ed. by L [ udwig ] Borkowski. Amsterdam, London: North -Holland Publ Comp / Warszawa: . Pol. Scientif. Publ 1970 ( = Studies in logic and the foundations of mathematics ). ISBN 0-7204-2252-3
• January Łukasiewicz: About the principle of contradiction in Aristotle. Hildesheim include: Olms, 1993 ( = The modern interpretation of Aristotelian logic; 5 ) (. Übs of ' O zasadzie sprzeczności u Arystotelesa ' Studyum krytyczne Kraków, 1910. )