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.
Hasan ibn Zayd Al-Ḥasan ibn Zayd ibn Muḥammad ibn Ismā‘il ibn al-Ḥasan ibn Zayd (Arabic: الحسن بن زيد بن محمد‎ ‎ ; died 6 January 884), also known as al-Da‘ī al-kabīr (Arabic: داعي الكبير‎ ‎ , "the Great/Elder Missionary"), was an Alid who became the founder of the Zaydid dynasty of Tabaristan.