 The most important center for mathematical logic was Warsaw.The Warsaw school of logic was headed by Jan Łukasiewicz (1878–1956) and Stanisław Leśniewski (1886–1939), professors at Warsaw University.The first of their pupils to achieve eminence, even before World War II, was Alfred Tarski (1902–83), from 1939 in the United States, where he became a professor at the University of California, Berkeley.