Cahit Arf's 100th Birthday

Source: http://www.google.com/logos/2010/arf10-hp.gif

Cahit Arf (18 February 1910 – 26 December 1997) was a Turkish mathematician. He is known for the Arf invariant of a quadratic form in characteristic 2 (applied in knot theory and surgery theory) in topology, the Hasse–Arf theorem in ramification theory, Arf semigroups, and Arf rings. [Read more on Wikipedia]