English: Jan Łukasiewicz (21 December 1878 – 13 February 1956) Polish logician and philosopher born in Lwów, Galicia, then Austria–Hungary. His work centred on analytical philosophy and mathematical logic. He thought innovatively about traditional propositional logic, the principle of non-contradiction and the law of excluded middle. Professor of Lvov University and Warsaw University. After WW II in exie, professor of University College Dublin.