Jan Łukasiewicz

Jan Leopold Łukasiewicz (21 December 1878 to 13 February 1956) was a Polish logician and philosopher, born in Lemberg, now Lviv, and best known for Polish notation and Łukasiewicz logic. His work centred on philosophical logic, mathematical logic and the history of logic. He was a pupil of Kazimierz Twardowski and took his doctorate in 1902. He taught at the University of Lemberg and from 1915 at the University of Warsaw, where he and Stanisław Leśniewski founded the Lwów-Warsaw school of logic. He was a pioneer of many-valued logic: his three-valued propositional calculus of 1917 was the first explicitly axiomatized non-classical logical calculus. He also applied modern logic to Aristotle's syllogistic. After the Second World War he settled in Dublin, where he held a chair of mathematical logic at the Royal Irish Academy until his death.