Jan Łukasiewicz (Polish: [ˈjan wukaˈɕɛvit͡ʂ] ⓘ; 21 December 1878 – 13 February 1956) was a Polish logician and philosopher who is best known for Polish notation and Łukasiewicz logic.[1] His work centred on philosophical logic, mathematical logic and history of logic.[2] He thought innovatively about traditional propositional logic, the principle of non-contradiction and the law of excluded middle, offering one of the earliest systems of many-valued logic.