Who did more ring theory, Cahit Arf or Sind ibn Ali?
Cahit Arf Cahit Arf (] ; 11 October 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.
Shimshon Amitsur Shimshon Avraham Amitsur (born Kaplan; Hebrew: שמשון אברהם עמיצור‎ ‎ ; August 26, 1921 – September 5, 1994) was an Israeli mathematician. He is best known for his work in ring theory, in particular PI rings, an area of abstract algebra.