Who did more ring theory, Cahit Arf or Sind ibn Ali?
Sind ibn Ali He is known to have translated and modified the Zij al-Sindhind. The Zij al-Sindhind was the first astronomical table ever introduced in the Muslim World. As a mathematician Sind ibn ʿAlī was a colleague of al-Khwarizmi and worked closely with Yaqūb ibn Tāriq together they calculated the diameter of the Earth and other astronomical bodies. He also wrote a commentary on "Kitāb al-ğabr wa-l-muqābala" and helped prove the works of al-Khwarizmi. The decimal point notation to the Arabic numerals was introduced by Sind ibn Ali.
Akhund Khorasani Mohammad Kazem Khorasani or Akhund-e Khorasani (Persian: محمد کاظم خراسانی‎ ‎ , (1839-1911)) was Twelver Shi'a Marja, politician, philosopher, reformer. He's regarded as one of the most important Shia "Mujtahid" at the time. He was a lecturer at Najaf seminary for years and significant number of students from "different regions of the Muslim world" used to participate his lectures. His most famous work is "The Sufficiency" (Arabic: کفایه‎ ‎ ) where he gathered the jurispurdential ideas such as `continuity` and "presented them in a yet more rigorous fashion as a unified theory of jurisprudence."