Jan Lukasiewicz

Jan Leopold Lukasiewicz lived from December 21, 1878, born in Lemberg, now Lviv, to February 13, 1956, when he died in Dublin, and was a Polish philosopher and logician. He is best known for inventing Polish notation, the prefix notation for logical and arithmetic expressions that bears his name, and for developing Lukasiewicz logic, one of the earliest systems of many valued logic. His three valued propositional calculus, introduced in 1917, is regarded as the first explicitly axiomatized non-classical logical calculus, and his work reshaped how the traditional principle of non-contradiction and the law of excluded middle were understood in propositional logic. He also produced influential scholarship formalizing Aristotle's syllogistic in modern logical terms, and is counted among the most important historians of logic.