1878 – 1956
Jan Łukasiewicz (1878–1956) was a Polish logician and philosopher, one of the founders of the Lvov-Warsaw School and a pioneer of modern mathematical logic. He is best known for inventing Polish notation (prefix notation) and developing multi-valued logics, including his three-valued logic designed to handle future contingents and the problem of determinism.
Developed Łukasiewicz three-valued logic (Ł3) as a formal response to the problem of future contingents
Invented Polish (prefix) notation, a parenthesis-free logical notation still used in computer science
Co-founded the Lvov-Warsaw School, one of the most influential analytic philosophy movements of the 20th century
Produced landmark historical-critical work on Aristotle's syllogistic and the principle of non-contradiction
Developed a family of many-valued logics (Łn and Łω) generalizing classical bivalent logic