Cahit Arf

Cahit Arf (1910–1997) was a prominent Turkish mathematician. He was born in Thessaloniki, then part of the Ottoman Empire, and his family later moved to Istanbul and then İzmir. He pursued higher education in Paris at the École Normale Supérieure on a scholarship and earned his PhD from the University of Göttingen under Helmut Hasse. Arf contributed significantly to various fields of mathematics, including algebraic number theory, topology, and algebra. His notable contributions include the Arf invariant, which has applications in knot theory and surgery theory, and the Hasse–Arf theorem in ramification theory. He also developed Arf semigroups and Arf rings. Throughout his career, Arf held academic positions at institutions such as Istanbul University, Robert College, and Middle East Technical University. He was also involved in establishing the Scientific and Technological Research Council of Turkey (TÜBİTAK) and served as its founding director. Arf received several honors and awards, including the Turkish Scientific and Technological Research Council (TÜBİTAK) Science Award and the French Commandeur des Palmes Académiques. He was a member of the Turkish Academy of Sciences and served as the president of the Turkish Mathematical Society. His portrait is featured on the Turkish 10 lira banknote. The Arf lectures are held annually in his memory.